By Gary Griggs, Distinguished Professor of Earth and Planetary Sciences, Director Institute of Marine Sciences, University of California, Santa Cruz, California

The Eastern Mediterranean, including dozens of Greek islands, have a complex geologic history. This area has been the site of both a primitive ocean that existed 250 million years ago that preceded the present day Mediterranean Sea, and also an area where several very large tectonic plates have been converging for eons.

The predecessor of today’s Mediterranean was known as the Tethys Sea and extended from the present day Mediterranean east to the early Pacific Ocean when there were no land masses in the way- no Middle East, no India, and no Southeast Asia. The Tethys was in a subtropical latitude and biological productivity was very high in the warm surface waters. Microscopic plankton flourished for millions of years, particularly those that formed calcium carbonate (CaCO3) skeletons such as planktonic foraminifera and coccolithophores. These shells accumulated to great thicknesses on the floor of this ancient ocean as a calcium carbonate or lime mud. Over time, with the increased pressure of the overlying sediment, this lime mud was compacted and consolidated; the water was squeezed out and it became limestone.

“The Eastern Mediterranean, including dozens of Greek islands, have a complex geologic history… ”
— Gary Griggs

A collision occurred perhaps 50 million years ago as the African Plate pushed northward and began to collide with the Eurasian Plate. This collision is responsible for pushing up the Alps, for example, which consist of the limestone that originally formed beneath the ancient Tethys Sea. This is the also the rock that many of the Greek Islands today consist of.

The thinner and denser plate beneath the southern portion of the Tethys Sea also began to be subducted or forced down beneath the Eurasian Plate. As the limestones were forced deeper into the crust, temperatures and pressures increased, and the limestone was recrystallized or converted to marble, which is still calcium carbonate. Limestone and marble occur throughout the Greek Islands, mainland Greece, and also through the Alps. The marble, the Carrara marble in the Italian Alps, for example, is the stuff Michelangelo carved. In Greece it is also the marble that the Parthenon and the other classical Greek temples and statues were built from. And it all started millions of years earlier as microscopic planktonic organisms that accumulated and were preserved on the Tethys seafloor.

There were also other processes going on during this tectonic collision. As the African Plate was subducted or forced down beneath the Eurasian Plate, the rocks and sediments that were carried down got hotter as they got deeper into the crust. These rocks begin to melt and the fluids that formed, being hot and under pressure, begin to rise in the crust, and ultimately were extruded out at the Earth’s surface as volcanoes. This is the same process that forms the volcanoes that virtually surround the Pacific Basin. In the Eastern Mediterranean the best known of these volcanoes today are Etna, Stromboli and Vesuvius in Italy, and the Greek islands of Aegina, Methana, Milos and Santorini or Thera, which lies north of Crete.

Volcanism first appeared on Santorini about 1.5 million years ago, and continued intermittently for thousands of years. About 3,600 years ago, however, there was a catastrophic eruption that blasted the top off the volcano and left a 32 square mile crater 1,300 feet deep and scattered volcanic ash across the eastern Mediterranean.

Deeper in the Earth, that molten rock that didn’t immediately make it to the surface as a volcanic eruption, cooled slowly to form granite. Some of that crystalline rock eventually was raised to the surface and today that granite forms the entire island of Mykonos and parts of the nearby islands of Naxos and Paros.

As a result of all of this tectonic upheaval, some of the Greek Islands consist of limestone, some marble, others are volcanic rock or granite, and some are sandstones and shales. As these different types of rocks weather and break down, and the broken fragments and grains are transported to the coast, either by small streams, or from the erosion of the coastal cliffs, they become rounded and smoothed. Whatever type of rock or rocks each of these different islands consist of, eventually ends up on the beach as sand, pebbles, shingles or cobbles. And these beaches can be strikingly different as a result of the geologic history and materials that make up each of the particular islands.

Mykonos and Paros, for example, have nice sandy beaches by virtue of the granite that makes up the islands. Granite breaks down into sand sized grains and, therefore produces sandy beaches. Santorini, is unique in being almost all black (and some red) volcanic rock, which as it finds its way to the shoreline, produces black and reddish coarse-grained beaches. Many of the other islands consist of limestone and marble, which doesn’t break down into sand. The fragments or small pieces of rock will first gradually get rounded and smoothed, but will gradually dissolve into the seawater. The beaches on these islands, Rhodes and Patmos, for example, and large parts of Crete, consist of smooth, sometimes flat pebbles (known as shingles) and not smooth and easy to walk on. So whether it is color or the size of the beach materials, you can find whatever you are looking for along the shorelines of different Greek Islands.

By William J. Neal Department of Geology, Grand Valley State University, Allendale, Michigan

“The sea gives and takes. The sea Devoured four houses one winter.”
— Excerpt from “Skara Brae” by George Mackay Brown (1921 – 1996)

Perceptions based on the present – what we see, hear, feel at the moment – bias our perception of the past and future. A static view of our environment is misleading. The human association with water, particularly shorelines, is a case in point. We do not perceive the history of place, and globally we occupy sites as if they are unchanging, not realizing that in fact they are of high risk. The following are the author’s impressions and personal discoveries from a couple of hours’ visit to Skara Brae, Scotland, site of a Neolithic village with origins going back 5000 years. This UNESCO World Heritage Site abounds in mystery, secrets yet to be discovered, and lessons to be derived. The poet, George Mackay Brown’s words, that the “sea gives and takes” reflects the history of Skara Brae’s discovery, partial loss, and is visionary in that the latter continues. Skara Brae, along with several other important archaeological sites in the Orkney Islands, are now in the “sea takes” category.

Skara Brae is now on the shore of Skaill Bay, Mainland, Orkney Islands, just off the northern coast of Scotland (Figure 1). The crescent-shaped beach at the head of the bay is subject to a high tidal range, and during Atlantic storms the shore is battered by very high wave energy (Figure 2). At spring low-tide there is a wide beach, but during the high tides the beach can be completely inundated. In 1850 a storm erosion at the back of the beach exposed some of the houses of the old Neolithic village, roofless but otherwise intact (Figures 3 and 4). The land owner initiated an excavation that continued until 1868, after which the site remained undisturbed, except for being raided for artifacts in 1913. The sea again took a bite out of the site during a 1924 or 1925 storm that destroyed one of the houses. The first-generation protective seawall was then built in the late 1920s, and has since been reinforced several times (Figure 5).

“The environmental setting of the village when first constructed has been determined to be well away from the ocean shore, behind protective dunes… ”
— William J. Neal

In viewing the village, one’s first impression is “why would they build their houses in such a hazardous place?” (Figures 4 and 5). But we must flash back from 5000 years ago to present in order to understand how the site came to be at the mercy of the waves. The environmental setting of the village when first constructed has been determined to be well away from the ocean shore, behind protective dunes, and near a freshwater lake. By that time, the rapid post-ice-age sea-level rise had slowed, but sea level was still rising. And the climate was changing. Very likely, the ocean shoreline was moving up the valley that is now the bay, and some archaeologists suggest that over time, the village was abandoned, perhaps because of storms moving sand dunes over the structures, as well as changes in the culture. In the sense of “the sea gives,” the dune burial preserved the village. Some millennia later, as the bay extended landward, the sea gave again when the 1850 storm revealed some of the village, before beginning the processes of “taking” by eroding the site.

Visiting the site during a low-spring tide reveals a beautiful beach; one in which the sediment distribution reflects the energy gradient of storm waves (Figure 6 and 7). The steep slope of the beach is apparent from atop the bluff, with cobble to boulder sized, flat flagstones at the uppermost back beach, a zone of more rounded cobbles to boulders at the base of the back beach, and the wide sandy inter-tidal beach on which ridges and runnels have developed (Figures 7 and 8). The flat flagstones are derived in part from the bedded sandstone outcrops that cross the beach (Figures 9 and 10). This island’s west coast is made up primarily of Devonian age sedimentary rocks, the “Old Red Sandstone”, which consists of these bedded sandstones and siltstones that have been referred to as ‘flagstones’ since the early days of quarrying, and are still used in construction. The flat stones in the walls of the Skara Brae houses were of the same origin, 5000 years ago.

The low-tide beach is a wonderful canvas on which a variety of bed forms have developed from waves and currents. Ripple marks can be seen in the runnels (troughs) as they drain, and the water-saturated sand from high tide drains during low tide, giving the beach mirror-like watery patches (Figure 8), and forming tiny rill marks from seeps (Figure 11). In places, one can see stripes of light and dark on the beach from truncated antidunes that formed during the falling tide (Figure 12), and beach cusps on a grander scale. The beach sand is generally fine to very fine, and poorly sorted with very small pebbles of dark gray siltstone. The light gray color of the beach reflects the varied sand composition (Figures 13 and 14), which includes a surprising amount of calcareous material from microscopic shells and skeletal fragments (e.g., clams, snails, forams, echinoid spines, and a lot of unidentifiable material). The darker shade is derived from black sand-sized rock fragments and mineral grains including biotite mica. Quartz grains are also common.

Not far from Skara Brae are other ancient sites (e.g., Maeshowe, Stones of Stenness, the Ring of Brodgar), but for this geologist the nearby Yesnaby coast was the highlighted contrast to Skara Brae beach. Yesnaby is a sheer rock coast – beachless with sea cliffs, stacks and arches. All cut in the “Old Red Sandstone” sequence including the Stromness Flagstones (Figure 15) in which one can find ancient ripple marks (Figure 16) and mudcracks on the bedding planes of these ancient lake deposits. And local beds contain fish fossils of the kind first described by Hugh Miller and his contemporaries in the 19th Century, in the days of the development of the science of geology in the British Isles.

For this author, Skara Brae was a place of discovery, that former civilizations did retreat in the face of climate change and associated hazards, that a poet understood better than most that the “sea gives and takes”, that there are a few places like Skara Brae where a seawall is justified (even there the wall contributes to nearby erosion), and, along with its Orkney sister sites, this Neolithic village is an example that a shoreline can be a reservoir to be ‘mined’ for knowledge rather than sand.

Figure Captions

• Figure 1. Outline map of the Orkney Islands at the northern tip of Scotland (circled area of UK inset map at lower right). The islands are at the boundary of the Atlantic Ocean (left) and the North Sea (right). The star marks the approximate location of Skaill Bay and Skara Brae on the western shore of ‘Mainland’, the largest of the islands.
• Figure 2. Google Earth image of crescent-shaped Skara Brae Beach at the head of Skaill Bay during low tide. Rocky headlands yoke the beach, and are probably a partial source for the beach sand which is mostly derived from reworking of earlier beaches and sand dunes that formed when the shoreline was seaward of its present position. Even in the satellite image the strong cuspate pattern along the beach is apparent, and one can discern a ridge and runnel pattern. The remnants of Skara Brae village lie atop a cliff/bluff of bedrock, capped by old sand dunes (lower left).
• Figure 3. Skara Brae’s Neolithic structures were preserved by being buried by sand dunes after their abandonment around 2200 B.C. The stone walls were constructed without cement, but the design and construction created below-ground dwellings that were water-proof. The furniture also was stone. Note people on beach (upper left) which gives perspective that village site is at top of bluff.
• Figure 4. Skara Brae structures. Note the beach in background (top), and the far bluff of dune sand that is retreating under the influence of storm wave erosion, exacerbated by the rising sea level. Brown wrack line on beach is from high spring tide. Note offset in shore line is past the position of the old village structures, now protected by a seawall (Figure 5)
• Figure 5. The seawall protecting the archaeologic site was constructed in the late 1920s after a storm had destroyed one of the houses in 1924 or 1925. The natural shoreline position has retreated past the line of the seawall. The erosion rate at the ends of the seawall has probably accelerated due to refracted wave energy.
• Figure 6. Skara Brae beach at low tide shows the ridge (outer bar) and runnel (trough) system. The water drainage is back flow from runnels that breaches the outer bar, as well as ground water draining from the beach. The brown wrack line in the foreground marks the level of the last high tide. Note the steep upper beach on which cobble to boulder sized material has been concentrated by storm waves, with flatter flagstones at top, and more rounded stones lower on the beach.
• Figure 7. View looking down the steep beach face from the sand dune cover to the flagstone zone, then rounded cobbles and small boulders, to the intertidal sandy beach. This sediment size/shape distribution reflects the energy gradient of storm waves. The largest storm waves toss the flat flagstones and slabs (cobbles to boulders) to the base of the eroding dune face, with a zone of more rounded stones in the same size range just seaward of the flagstone zone.
• Figure 8. This view of the low-tide beach also shows the size-sorting pattern as well as the character of the sandy beach. Standing water in the runnels and water seeps along the mid-beach face produce mirror-like surfaces.
• Figure 9. Close-up of the flagstones. The similarity of these beach rocks and the construction materials of the Neolithic structures are obvious. Given that a similar beach would have been farther from the village site at the time it was occupied, the convenience of the shape of the stones would have made their transport worthwhile.
• Figure 10. The beach outcrop of a rock unit producing flagstones explains in part the source of these rocks on the upper beach. But some of the beach materials probably have come from the erosion of the nearby headlands.
• Figure 11. In addition to the larger drainage patterns on the beach (Figure 8), the micro drainage produces smaller bedforms as water seeps from the beach. Rill marks are like micro-canyons cut by the running water. Small 20p coin for scale.
• Figure 12. Note the striped pattern (dark and light) at the back of the sandy beach (mid-photo). This pattern of truncated anti-dunes forms by wave swash/backwash on the falling tide, and is a fairly common bed pattern on high-energy beaches.
• Figure 13. The light gray color of the beach sand is due to a fairly high content of dark-colored sand grains. The sand is poorly sorted, but generally fine to very fine in grain size, with some coarser granule to small pebble-sized rock fragments of dark gray siltstone. Dime for scale.
• Figure 14. A microscopic view of the beach sand shows a surprising amount of calcareous material derived from shelly organisms; the white chalky grains, as well as very fine fragments of thin shells. Whole microscopic snails, clams, and possibly forams were noted. The darker grains include sand-sized rock fragments and mineral grains including black biotite mica. Scale divisions equal mm.
• Figure 15. The sea cliffs at Yesnaby include the beautiful Stromness Flagstones formation which consists of moderately thin beds (flags) of sandstones and siltstones, part of the “Old Red Sandstone” sequence (Devonian). Not far from this location is a unit containing fish fossils for which the “Old Red” became famous for all over the British Isles in the mid-19th Century.
• Figure 16. Ripple marks on the bedding planes of these sandstones and siltstones formed around 400 million years ago when these sediments were deposited in an ancient lake basin. These bedforms are not unlike the ripple marks you might find today on the beach at Skara Brae.

References

• Fraser, R., 2001, George Mackay Brown and the Orkney Islands.The Sewanee Review, 109 (4), 564-73.
• TGeologic map
• Markham, A., 2017, Heritage at Risk: How Rising Seas Threaten Ancient Coastal Ruins.
• Miller, H. 1841, The Old Red Sandstone, or, New walks in an old field (1st ed.). John Johnstone, Edinburgh.
• Sargent, G., 2019, Climate change endangers Scotland’s archaeological treasures. World News, October 10, 2019
• Wilson, P., (editor), 2005, Building with Scottish Stone. Scottish Executive National Science Institute, Arcamedia, Edinburgh, 64p.

By Robert Young, Margarita Stancheva and Hristo Stanchev

Originally published on: May 1st, 2014

In the middle of the Bulgarian Black Sea coast is Kamchia-Shkorpilovtsi beach, the longest sand beach in Bulgaria. The beach lies between two rocky headlands (Ilandgik and Cherni nos) and is located approximately 30 km away from Varna Bay (Fig. 1 and Fig. 2). Kamchia-Shkorpilovtsi beach begins 2 km north of the Kamchia River mouth and ends 2.5 km south of the mouth of Fandakliyska River. The name of the beach originates from its close proximity to the Kamchia River and Shkorpilovtsi village located further inland.

Kamchia-Shkorpliovtsi beach is a popular site for swimming, both for locals and for Bulgarian and foreign tourists. The beach is fairly undeveloped and natural, in particular in its southern part. The northern portion of the beach near the Kamchia River mouth has a few hotels for tourists and children’s groups from Russia who spend summer holidays in Bulgaria. Thanks to the lack of large hotels, the beach looks almost wild, even in the summer, and it is a preferred area for people who are seeking natural beauty and relaxation. The coastline here is straight and has an eastern exposure and the dominant winds blow from NE, E and SE directions.
The strong waves approach the shore mostly from NE and E, which makes the beach area one of the best on the Black Sea to practice surfing, windsurfing and kite surfing.

The research base of the Institute of Oceanology (IO-BAS) is located on the beach near the mouth of the Fandaklyiska River and includes a research station and a pier. There is work and living space for 35 people. The pier itself is 230 m long and 7 m high, and is used for mounting research gauge and other measurement equipment.

The Kamchia River is the longest river in Bulgaria and on the Balkan Peninsula to flow directly into the Black Sea, with a length of 244.5 km, has a catchment basin of 5357.6 km2 and an average water amount of 19.25 m3/s. The Kamchia starts at the confluence of two rivers springing from Eastern Stara Planina (Golyama Kamchia and Luda Kamchia), flows eastward to the Black Sea and empties into it 25 km south of Varna (Fig. 3).

“ The Kamchia River basin contains the best preserved flooded forests along the Bulgarian Black Sea coast.”
— Margarita Stancheva, Rob Young & Hristo Stanchev

The Kamchia River basin contains the best preserved flooded forests along the Bulgarian Black Sea coast. These low-lying forests, called “Longoz,” are a unique example of this type of habitat across Europe. Because of the need for environmental protection, this area was declared a natural reserve in 1951 by the Ministry of Forests and in 1977 it was included in the global network of biosphere reserves as part of the UNESCO “Human and Biosphere” Program. This network of reserves includes the protection of the most representative ecological systems on the planet. The forest is typically flooded by the Kamchia River, related to seasonal water level changes, which has led to strong vegetative growth that in places is almost impenetrable.

After its expansion in 1980, the reserve covers 842.1 hectares (ha) of wet forests by the mouth of the river. The lowest lying sections of the “Longoz” forests resemble a jungle, with creepers interweaving with trees or hanging down like thick draperies. Twenty-three fish species and numerous mammal species are found in the waters of the river and the adjoining marshlands. One of the most interesting features of these forests is the feathered inhabitants. Kamchia is situated on the migratory flyway “Via Pontica,” which allows for the observation of various bird species that stop to rest and feed during migration. Many interesting and rare birds breed in the area, such as Black Stork, Lesser Spotted Eagle, Great Spotted and Lesser Spotted Woodpeckers, Tawny Pipit, Barred Warbler, Semi-collared Flycatcher and Icterine Warbler. Visitors traveling through Kamchia reserve must follow marked paths and specified rules.

Kamchia-Shkorpilovtsi beach is 12.4 km long, with an area of 500 294 m2 and about 25 m average width. In the northern section, where the beach and sand dunes are leveled by bulldozing, it is up to 110 m wide (Fig. 4). The adjacent coast is built by limestones, Paleogene sandstones, marls and clays, and in Eastern Stara Planina by Upper Cretaceous sandstones, aleurolites, argillaceous rocks and limestones. The average rate of erosion of these rocks is 0.16 m/y.

The beach is composed of fine to medium quartz sands with low carbonate content (3-8 %), which originate from the erosion of the sandstone rocks outcropping at the coast. These sandstones consist of 80% quartz grains cemented with lime substance brought from the Kamchia and Fandakliyska rivers.

There are well-developed foredunes on the back side of the beach. Landward of these foredunes are vast fields of stabilized and vegetated dunes, followed by forested dunes located further inland. Dune systems occur behind the beach, where their development has been favoured by the dominant wind direction and ready supply of sediment (Fig. 5).

Near the mouth of the Kamchia River, there is a large dune bar parallel to the coastline, which has a maximum height of 6 m. Since the coast here is exposed to NE, E and SE winds, a number of dunes with heights up to 8 m are formed landward just behind the bar. Similar climate conditions (dominant winds from E, NE and SE directions) have also shaped a comparable dune landscape around the southern part of the beach, distinguished by large foredunes and parallel dunes located inland (Fig. 6).

Just offshore, the coastal slope is shallow and primarily comprised of sands and aleurolites (silt sediments). The northern section is commonly 500-600 m wide and the widest section is 1 km near the mouth of the Kamchia River. The boundary between sands and aleurolites is at a depth of approximately 20-25 m, but near the river mouth this boundary can be found at shallower depths (around 8-12 m). This is a result of the large amount of alluvial material being deposited by the river.

A rocky platform at a depth of 6 m and 30-40 meters wide stretches intermittently along much of the shoreline near the mouths of the Kamchia and Fandakliyska rivers. This platform consists of lime sandstones and has an asymmetrical shape, with the highest part next to the shore. This rocky platform is a natural defense of the existing beach from direct wave impact.

As the beach is still undeveloped and has no coastal protection structures, its dynamics remains natural and fairly stable. Winter storms commonly cause erosion, as strong waves reshape the beach profile and reach the backshore, thus causing erosion of the foredunes as well. However, in the summer the beach returns to its stable condition. Sands are transported alongshore from north to south, as it is the general sand transport direction for the entire Bulgarian coast. Although the beach is generally stable, strong storm waves can flood the beach and provoke erosion of the foredunes and even of relict dunes located at some distance landward (Fig. 7).

Until the early 1990s Kamchia-Shkorpilovtsi beach was characterised mostly by accumulation; previous research by Dachev et al. (2005) found that between 1958 and 1991 the shoreline migrated seaward 12.7 m. The situation has changed over the years as a result of human impacts on the Kamchia River, primarily hydraulic construction such as artificial lakes, long impermeable river corrections and engineered defense structures. The natural river flow and sediment load has been disturbed causing a sediment deficit along the shoreline. In addition, the decrease in discharge of solids has been exacerbated by the extraction of sands and shingle material from the river bed. In the entire catchment basin of the Kamchia River, 82 artificial lakes were built. After construction of three artificial lakes during 1972-73, the discharge of sediments of the Kamchia River decreased from 2 000 000 t/y to 500 000 t/y. As a consequence, the sediment balance in the Kamchia River area has been disturbed and this has adversely impacted Kamchia-Shkorpilovtsi beach by reducing beach area and width. The most recent observations (2013) for the period 1983-2011 indicate that although erosion rates are low, the shoreline has retreated 2.30 m or 0.08 m/y (Fig. 8).

Sand dunes are active on the backshore of the beach and become more stabilized and fixed landward as they are covered with vegetation and forests. Located between the mouths of the Kamchia and Fandakliyska rivers, is the largest dune complex on the Bulgarian coast. This dune complex is made up of shifting, stable vegetated and rare grey dunes (grey stabilised dunes with wet dune slacks and forested dunes, Fig. 9) and is 7180 m long with an area of almost 2 km2. The complex is a priority conservation habitat in the European Union. The beach and foredunes (mobile) are characterized with typical psammophyte vegetation (Fig. 10).

“ As the beach is still undeveloped and has no coastal protection structures, its dynamics remains natural and fairly stable.”
— Margarita Stancheva, Rob Young & Hristo Stanchev

Even though the beach and dunes still remain less urbanized and are subject to legal protection, they have been exposed to some human-induced threats, such as litter from tourists. Additional litter and industrial pollutants regularly wash up on the shore, much of which comes from either the port of Varna or ships traveling just offshore.

Other threats to this coastal area include: 1) unregulated camping and “temporary” construction on the beach and dunes, 2) a lax regulatory environment that tolerates the re-zoning of protected sand dunes to “agricultural” areas (thereby allowing for easier transition for development), 3) sand compaction and destruction of rare dune habitats during the summer when large numbers of tourists cross the dunes to reach the beach, 4) off-road driving and parking, 5) illegal sand extraction, 6) afforestation with non-native species, such as Pinus Maritima which was introduced in the 1970s leading to the degradation of dune habitats here (Fig. 11).

The most impacted section of Kamchia-Shkorpilovtsi beach is to the north near the Kamchia River mouth. Along this developed portion of the shoreline, the beach and dunes have destroyed by bulldozing and leveling. Although the beach is not overdeveloped, it has been the most impacted over the past decades and it is unknown whether these dunes will naturally recover.
The expansive dune fields and beach are collectively referred to as “Kamchia sands.” In 2006, an investor succeeded in removing the protection status of these beach and dune areas. Due to its high conservational value, the protected area is also subject to the Environmental Network NATURA 2000 of the European Union, Ramsar Convention on wetlands, Council Directive 92/43 and other conventions. Therefore, one of the major threats to Kamchia-Shkorpilovtsi beach is the elimination of the protected status of “Kamchia Sands.” There is also a threat of ending the conservation status of the area because of logging and construction of hotels and supporting infrastructure on the shoreline.

Kamchia-Shkorpilovtsi beach is the longest beach in Bulgaria and is distinguished by vast areas of preserved rare sand dunes which are a priority habitat in Europe. For many years prior to human construction on the Kamchia River, the beach remained stable and did not experience significant erosion. Although erosion rates are still relatively low, the shoreline has been retreating since the early 1990’s. We suggest that if the beach remains naturally functioning, its dynamics and morphology will not experience large changes in the near future. The only real threat to the beach is associated with coastal development plans to build new infrastructure that will increase tourism.

• 1. Council Directive 92/43/EEC of 21 May 1992 on the conservation of natural habitats and of wild fauna and flora. Official Journal of the European Union L 206, 22.7.1992, p. 7.
• 2. Dachev, V.Z., Trifonova, E.V. and Stancheva, M. K. 2005. Monitoring of the Bulgarian Black Sea Beaches. (In), Guedes Soares, Garbatov & Fonseca (eds.) ‘Maritime Transportation and Exploitation of Ocean and Coastal Resources’Taylor & Francis Group/ Balkema, 1411 – 1416.
• 3. NATURA Project stuff, 2000. Preparation of the Bulgarian Natura 2000 Network of Protected Zones.
• 4. Peychev V. and Stancheva, M. 2009. Changes of Sediment Balance at the Bulgarian Black Sea Coastal Zone Influenced by Anthropogenic Impacts. Compt. Rend. Acad. Bulg. Sci, 62, 2, 277-285.
• 5. Peychev V. 2004. Litho- and morphodynamic of the Bulgarian Black Sea coastal zone. Publ. House “Slavena”, Varna, 231 p. (In Bulgarian).
• 6. Sixteen cases of Natura 2000 vandalism in Bulgaria. Retrieved in pdf from: BirdLife International
  (http://www.birdlife.org/eu/pdfs/Nature_Directives_material/Portfolio_texts%20_final.pdf ; last accessed on 23.01.2014).)
• 7. Stancheva, M., 2010. Sand dunes along the Bulgarian Black Sea coast. Compt. Rend. Acad. Bulg. Sci., 63 (7), 1037-1048.
• 8. Stancheva, M., Ratas U., Orviku K., Palazov A., Rivis R., Kont A., Peychev V., Tõnisson H. and Stanchev H., 2011. Sand dune destruction due to increased human impacts along the Bulgarian Black Sea and Estonian Baltic Sea coasts. Journal of Coastal Research, SI 64 (Proceedings of the 11th International Coastal Symposium), 324-328, Szczecin, Poland, ISSN 0749-0208.
• 9. Tzonev, R. 2011. Red Book of Bulgaria, Volume 3, Natural habitats. Issued by Bulgarian Academy of Sciences and Ministry of Environment and Water of Bulgaria.
• 10. Tzonev, R.; Dimitrov M. and Russakova, V., 2005. Dune vegetation of the Bulgarian Black sea coast. Journal Hacquetia, 4 (1), 7-32.
• 11. Kamchia (biosphere reserve)
• 12. Bulgaria Travel- Kamchia Reserve
• 13. Kamchia Biosphere Reserve

Black Sea Coast of Bulgaria, Flyover: A Photo Gallery, By The Program for the Study of Developed Shorelines (PSDS)

The Program for the Study of Developed Shorelines (PSDS) collaborated with the Bulgarian Academy of Sciences Institute of Oceanology (IO-BAS) to conduct the first comprehensive photo survey of the Bulgarian Black Sea Coast. Images were acquired July 10 and 11, 2013.

The flight progressed from the Romanian border in the north to the Turkish border in the south with close to continuous coverage. The project was funded jointly by PSDS and IO-BAS along with support from the Bulgarian Fulbright Commission.

In celebration of Coastal Care’s 10 years Anniversary, we are republishing an acclaimed selection of the most popular Beach Of the Month contributions.
“Our Deepest Gratitude And Thanks To Our Talented And Inspiring Beach Of The Month Authors Contributors —Santa Aguila Foundation – Coastal Care”

By Andrew Cooper, University of Ulster

Originally published on: January 1st, 2010

Anegada, the most northeasterly of the British Virgin Islands is a sandy island that sits on top of a Pleistocene reef that is now exposed above sea level. The island’s northern shore has a wide modern reef terrace that supplies broken down shell materials for a sandy beach that runs along the entire northern shore of the island for almost 20km. The fine white sand of the beach, palm trees and the aquamarine colour of the sea create a classic tropical beach landscape. The sparsely-inhabited island has a few tiny beach resorts (comprising a bar and/or a few holiday cottages) such as Cow Wreck Bay (named after the wreck of a ship carrying a cargo of cows), and Loblolly Bay.

Although the island is exposed to Atlantic waves, most of them break on the wide reef and lose most of their energy before reaching the beach. The beach is therefore well protected and historically the shoreline has been quite stable. Despite this, there are local areas of erosion that are probably created by local sediment scarcity as sediment moves along the shoreline. At one such area, west of Cow Wreck Bay, the coastline has been retreating for a few years. Unfortunately, this was one area in which a few holiday cottages had been built. One cottage has now (October 2009) been undermined by shoreline recession and is falling into the sea. Another will soon go the same way. Not far away along the coast to the east, is an undeveloped area where, ironically, the beach is advancing. That area, however, has a well-defined dune scarp that indicates that until recently, it had been eroding. The situation of alternating areas of erosion and accretion suggests that this stretch of coast, while protected from high wave energy, advances and retreats locally as the available sand moves along the coast creating local deficits and surpluses. Fortunately no shoreline stabilization has taken place on the north side of the island and the coast remains free to fluctuate in response to waves and sediment variability and so retain its natural beauty.

The photographs show the natural beauty of the Anegada north shore beaches on a stable section of coast, an area that was once eroding but which is now accreting seaward, and an area of active erosion. The collapse of a holiday cottage is also shown, which, while bad news for its owner, is good news for the beach.

In celebration of Coastal Care’s 10 years Anniversary, we are republishing an acclaimed selection of the most popular Beach Of the Month contributions.
“Our Deepest Gratitude And Thanks To Our Talented And Inspiring Beach Of The Month Authors Contributors —Santa Aguila Foundation – Coastal Care”

Nelson Rangel-Buitrago, Adriana Gracia, Grupo de Geología, Geofísica y Procesos Marino-Costeros, Universidad del Atlántico Barranquilla, Atlántico, Colombia, and William J. Neal Department of Geology, Grand Valley State University, Allendale, Michigan.

Recall the proverbial “canary in the coal mine” – miners carried the bird in a cage to measure air quality; dead bird, get out of the mine! Santa Veronica Beach, Colombia, is a model for the “canary in coastal development.” The community of Santa Veronica owes its existence to the recreational beach (Figure 1), and the economies of the adjacent communities of Santa Veronica Cajacopi and Salinas del Rey are tied to this beach tourism (Juan de Acosta Municipality). Santa Veronica is one of numerous recreational beach developments along Colombia’s Caribbean Coast (Figure 2); most sharing a similar history of shoreline retreat, perceived as shoreline erosion, and the attempt to hold the shoreline in place through the use of shore-hardening structures.

While the authors were conducting a regional study of Colombia’s Caribbean Coast, they revisited Santa Veronica beach to conduct drone flights (Figure 3). These aerial views, as well as ground level observations on the shore, revealed problems that are at the core of an on-going controversy over the conception of shoreline erosion, and how the local vendors were responding to their beach-front losses of kiosks and other structures. On 15 March 2019 the headline of the El Heraldo (Baranquilla city newspaper) was “Coastal Erosion also Hits Juan de Acosta” (English translation) with a photo of locally-made gabions forming a short wall, already swamped by waves. And on 1 April the El Tiempo news headline was “Santa Verónica fights so the sea does not swallow its beaches” (~English translation). How did it come to this?

Natural Setting

The Caribbean coast of Colombia has a rich geological, biological and cultural diversity that is reflected in a unique coastal zone extending from Venezuela to the Panama border. This coast is the first region that revealed the beauty of Colombia to the world with the golden walls of old Cartagena, the white sandy beaches of the Rosario Islands, and the green maze of Tayrona National Park (see Coastal Care, Beach of the Month, 2017-09/10). In the central part of this coast is the Atlantico Department shore, a 72 km long reach that lies predominantly in a NE–SW orientation with some sectors oriented E-W (Figure 2). This complex coastline’s geomorphology was determined by tectonic processes, landward surface erosion, and oceanographic processes, resulting in a shoreline of sandy beaches, sand spits, dunes, rocky coasts, lagoons, and some mangrove swamps (Rangel-Buitrago et al., 2018).

“Santa Veronica is one of numerous recreational beach developments along Colombia’s Caribbean Coast; most sharing a similar history of shoreline retreat… ”
— N.Rangel-Buitrago, A. Gracia & W. Neal

The Department’s coastline is a developing area with 1,378,800 inhabitants (Gracia et al., 2018), representing close to 4% of Colombia’s total population, and located primarily in Barranquilla, the largest and most populated urban concentration on Colombia’s Caribbean coast. The region’s coast currently is an emerging tourist destination for both Colombians and international visitors. The attractive landscape, good weather conditions, and the increased capacity for the practice of adventure sports are major attractors for this area.

Santa Veronica is part of this semi-arid tropical environment (mean temperatures of <28ºC and maximum precipitation values of 2,500 mm/yr), and coastal amenities make the village beach a prime attraction for tourism development (Rangel-Buitrago et al., 2013). But this development apparently has overlooked some other aspects of the environment and climate that offset the ‘paradise’ of Sand-Sea-Sun attractors. In particular are wave energy, especially associated with storms, the sensitivity of the beach to its sediment supply, and how these relate to the gradual sea-level rise — all now being expressed in the landward migration of the beach.

Santa Veronica Village has long been a beach-tourism hot spot, first for locals but now tourists from a broader spectrum. The beach and community encompasses an area of 3.8 km2, with 17,925 inhabitants. Specifically, the Santa Veronica coastal zone is a 1.2 km length shoreline segment composed by 650 m of beach and 550m of cliffed coast (Figure 3). This beach is part of a shoreline reach, including adjacent communities, that forms a shallow pocket between the shadow of Cerro Furu at the northeast end to Punta de Piedra at the southwestern extremity.

Seasonal variations consist of two rainy periods (April-May and October-November) and two dry periods (December-March and July-September). Winds have average velocity values lower than 13 m/s. The larger wave-generating, higher-velocity winds are those blowing from the NE during the dry season. Lower velocity values are observed between September and November when winds blow from the East (Anfuso et al., 2015). The average significant wave height is 1.5 m and peak period average is 7.5 s. From November to July, the wave system along the area is dominated by NE swells; while for the remainder of the time, waves from NW, WSW, and even SW occur (Gracia et al., 2018). Tides are mixed semi-diurnal, with maximum amplitudes of 65 cm typical of a micro-tidal environment (Rangel-Buitrago et al., 2017).

Longshore sand drift has a dominant south-westward component, and this pattern is reflected in the groin-effect discussed below, as well as the greater abundance of sand along the SW part of the reach where sand dunes have formed (Figure 4). A minor reversal in the drift pattern, back to the northeast, occurs during rainy periods when southerly winds prevail in some areas, and set up short, high-frequency waves capable of generating significant sediment transport along sandy beaches (Figures 3 and 5). The headland and associated shallow-submerged bedrock ridge at the NE end of Santa Veronica beach creates a wave-refraction pattern that favors beach formation beyond that point (Figure 6).

A small portion of the beach sediment supply comes from the erosion of Tertiary sandstones that outcrop in these headlands (Figure 5). However, rivers are the ultimate major sand-sediment source to Santa Veronica beach, but this sand’s immediate availability is strongly controlled by the seasonal wave regimens that influence the strength and direction of long-shore drift. This supply of coarse terrigenous sediments comes mainly from the distant, large Magdalena River and three small distributaries which drain the Santa Veronica area. Historically, after the emplacement of the Magdalena River jetties, the old delta broke up and large sand bodies moved SW along the coast, sometimes coming on-shore to form or nourish sand beaches. However, these occurrences were temporary, and the resulting beaches lost their sand sources.

Brief History

Based on the newspaper interviews with locals, Santa Veronica originated in the mid-20th century, and reminiscences older inhabitants indicate that the beach was considerably wider in those early days. Stories of patron saint activities on the beach and playing football (soccer) on a wide beach area that is now under water. That wide-beach scenario began to change in 1988 with the passage of Hurricane El Joan. Cero Furu began to erode, taking away some of its protection of the beach in its shadow, and the beach also began to retreat. The apparent response to that impact was the construction of the large groin which, again as a local put it, precipitated an added erosion problem, recognizing that the groin blocked the down-drift sediment supply (“there is no beach because there is no sediment” – El Tiempo, 1 April 2019). After the emplacement of the groin, the responsibility of battling the shoreline retreat fell to the property owners, and again the interviewees noted that they’ve been trying to hold back the shoreline for at least 20 years. In this same time span Santa Veronica has experienced a population growth of 24% (Figure 7), accompanied by development crowding the shore with a corresponding loss of habitat (coastal squeeze).

Wrong Responses

Every year seasonal changes to the beach profile, although natural, are a severe problem to Santa Veronica inhabitants. Because there is no room to accommodate the shoreline advance, the kiosks and other buildings of the coastal squeeze are threatened by erosion or flooding (Figure 8). These seasonal and regular changes produce beach narrowing and inundation, deterioration of scenic quality, and loss financial investments resulting in seasonal construction of hard-protection structures that basically have little or no functionality, and ultimately contribute to both more beach loss and wasted finances. This squeeze of beach and the associated line of losing structures has become an obstacle hindering the economic growth of the village.

Currently, Santa Veronica beach only works on an ‘action-reaction or post-disaster’ basis, i.e., management initiatives are triggered each year by emergencies and not risk prevention. Every year history repeats itself:‘protective’ structures are built or installed in response to local stakeholder pressure when properties are exposed to destruction, without carrying out required environmental impact assessment or preliminary potential risk and collateral-effects evaluations.

The ‘urgent apparent coastal erosion solutions’ (gabions, sand bags, and litter used to construct walls and groins) are emplaced in order to quickly reduce the immediate perceived erosion process impact (Figure 9). Unfortunately, every year the clear lesson is that these ‘fast’ coastal defense structures are useless. So annually the next step is to petition for government help. In 2019 the immediate help came through the township Mayor’s office with a few thousand dollars’ worth of materials (e.g., stones and wire mesh) for the locals to build gabions, and repeat the folly. On a grander scale, regional government has proposals on the table including building a sand berm, that suspiciously sounds like they will rob sand from other beaches or dunes where ‘there is no erosion problem,’ or build as many as 11 additional groins (presumably larger than those built by the locals). In response to this latter proposal at least one old-timer had the wisdom to respond ‘…tourists do not want to come to look at stones but to contemplate the sea and bathe…’ (El Tiempo, 1 April 2019).

What else could go wrong? Litter

Santa Veronica beach is plagued by another negative aspect of Colombia’s Caribbean Coast – litter, both natural and man-made. The natural litter is drift wood – tons, and tons of driftwood – logs, branches, stumps with roots, covering beaches. Most of these tree remains are believed to have come from the Magdalena River, and probably have made more than a few stops along beaches on their way to the Southwest. In addition, there is man-made lumber adding to the wood volume, and large amounts of refuse dominated by plastics, but including a wide range of materials (e.g., metal, glass, processed wood, and rubber, among others – Gracia et al., 2018). These man-made materials come from two main sources – the long-shore drift and the trash left behind by beach users. The locals clean up the Santa Veronica beach, but untended beaches in adjacent areas commonly have lots of beach litter (Figures 10 and 11). We are now coming to realize that there is another aspect of beach litter that has a negative side. Encrusting marine organisms, always in search of hard surfaces for attachment, are now commonly found on beach litter (Figure 12). And some of these organisms can travel very long distances on the flotsam, allowing alien species to invade local marine habitats (Gracia et al., 2018).

Santa Veronica’s Lessons

In Santa Veronica’s relatively short history, those who built their homes and businesses close to the beach probably thought in terms of the shoreline being static. Old timers have had the life experience of discovering that the shoreline is dynamic, and that they are ever closer to the beach and its associated storm waves and inundation. Those who had property threatened or lost, responded in a common way, doing what seemed logical – solidify the shoreline by building walls and groins. Such empirical construction of seawalls and groins (whether from strong materials such as rip-rap, or weak construction such as gabions and sandbags) is a common practice along the entire reach of the Caribbean Coast of Colombia. Unfortunately, a significant percentage of people do not know the function of these structures and their negative impacts, especially when constructed with limited design information or knowledge of their confirmed negative impacts. In many instances, people with no knowledge regarding the causes of erosion, try to resolve the problem intuitively. Usually, coastal inhabitants collect stones from nearby quarries, produce low-cost concrete blocks, use concrete remains, tires and in some cases litter to build such structures to stop the perceived erosion.

“The managed/planned retreat option seems an inevitable solution and probably the most appropriate solution for the human settlement at Santa Veronica as well as much of Colombia’s coast… ”
— N.Rangel-Buitrago, A. Gracia & W. Neal

Now the village is caught in the squeeze, and faces several unanticipated challenges from the impacts of increased regional population such as the pressure of increased development in the coastal zone (more beach users, more litter and pollution) to the impacts of climate change in terms sea-level rise and possibly increased storminess.

The managed/planned retreat option seems an inevitable solution and probably the most appropriate solution for the human settlement at Santa Veronica as well as much of Colombia’s coast. Managed/planned retreat has the primary objective of reducing population, property, and infrastructure at risk through the planned withdrawal from coastal hazard zones, including dynamic or erosion-prone areas (Neal et al., 2018 and Rangel-Buitrago and Neal, 2018).

Specific to Santa Veronica Beach, a managed retreat approach will help to move existing and proposed tourism development of most sensitive areas out of harms’ way. Along the entire reach, this approach may include managed realignment where shore-protection structures can be removed to allow the natural coastal environment to be re-established (i.e., the old big groin). Here the management approach must be based on the simple philosophy to get out, avoid damage, and recognize that the coastal zone dynamics should dictate the type of management employed: do not build/rebuild over the same shoreline.

The lesson from the Santa Veronica canary is that coastal management demands techniques, knowledge, equipment and institutional instruments to minimize or avoid coastal erosion, and if that is not possible then to reduce the impacts. The management should be optimally beneficial in reducing both the vulnerability of the coast or in reducing the effects of coastal natural changes or coastal erosion. Under current and projected future climate change developments, any management strategies should allow coastal communities to minimize their detrimental impacts on natural ecosystems while maximizing the benefits of the latter. Introducing new management strategies for a developed community such as Santa Veronica is difficult but not impossible, and there are numerous communities where development has not reached this stage that can benefit from the bad experiences of others. One has only to look at the shores of the adjacent communities within Juan de Acosta to see they have a chance to establish strong management goals. Yet the old patterns are already repeating themselves (Figures 14 and 15). Are we at a tipping point (Figure 16)?

Figure Captions

• Figure 1. NE Santa Veronica’s wider beach segment on a quiet day. The local economy is sand-sea-sun based, but the beach is narrowing. Note the dry-beach width narrowing toward the beach-less headland. The storm-wave breaker line is into the trees, flooding kiosks and business stands.
• Figure 2. Santa Veronica is about 35 km SW of the mouth of the Magdalena River. The recurved coastal segments are characterized by beaches between headlands, or barrier beaches fronting lagoon, and beaches associated with spits.
• Figure 3. Santa Veronica squeezes against a landward retreating shoreline, and the natural beach depends on interaction between ocean and landforms. Note the refracted wave pattern around the eroding headland, favoring some sand accumulation at the NE end of the beach. The line of breakers almost perpendicular to the shore is due to a shallow ridge of bedrock.
• Figure 4. Sand dunes at the SW end of this shoreline reach, fronting Salinas del Rey, reflect the SW trend of the longshore drift, and increased sand supply sufficient for dune formation.
• Figure 5. The predominant longshore drift to the SW is reflected by the pattern of sand trapping up-drift of the groin. Note the beach narrowing on the right of the groin, and its position farther landward, reflecting sand starvation on the down-drift side of the groin.
• Figure 6. The headland of outcropping Tertiary age sediments is a local source for some of the beach sand, although the ultimate source of beach sand here is from Magdalena River sediment input and longshore drift. Note the beach is narrow to absent around the headland, and in the lower photo one can see slabs of concrete, probably from earlier failed seawalls. Coarse debris dumped on the shore bank offers little protection from storm wave erosion.
• Figure 7. Comparison of the Santa Veronica development from 2003 to 2019. Note the large increase in housing. Shoreline changes are more difficult to discern as the vegetation line obscures the position of the back of the beach. One suspects that the wet-beach line has moved landward, while the kiosks and small buildings have been constructed closer to the sea – the coastal ‘squeeze’.
• Figure 8. The response to the landward migration of the beach has been individualistic, trying to hold the shoreline in place with whatever materials were available. Building walls or small groins with driftwood, sand bags, tires, and rock debris, resulting in a trashed beach, and still losing ground to the sea.
• Figure 9. More recently, with some minor assistance (loads of rock, wire baskets, and bags to fill), the same small-scale attempts to hold back the sea with gabions and sand bags will continue to fail. Gabions are a poor choice of construction material for seawalls and groins for several reasons. Note here that there is no top on the gabion wire basket. Storm waves will force the rocks out of the basket, littering the beach with sharp, angular stones that will not be welcomed by beach users. Sea water and wave/sediment abrasion will also result in failure of the gabion, which clearly has already been flanked by waves rendering it useless as a ‘protective’ measure. And size of structure doesn’t preclude failure. Note in the lower right photo that the large groin has been a significant contributor to down-drift erosion. No dry beach exists to the right of the groin. Why would property owners want additional structures of this sort? When their beach is gone, the tourists will be too.
• Figure 10. Santa Veronica beach is littered with both natural flotsam (wood) and trash, either arriving as flotsam or left behind by beach users. Locals clean the beach daily, piling the litter to be hauled away. However, sometimes wave run-up scatters the litter again before removal.
• Figure 11. Driftwood is abundant on many Colombian beaches, coming in part from local erosion, but mostly from the Magdalena River. Santa Veronica Cajacopi beach is covered with logs and branches that may give a slight natural protection to the beach by trapping sand, but in storms, these logs can become battering rams. In addition to limiting access by beach users, the maze of wood debris traps the abundant man-made litter from the longshore drift. Clearly, this litter is dominated by plastic, but larger items are common.
• Figure 12. Marine organisms attach to both man-made and natural flotsam. Here on Santa Veronica Cajacopi beach bryozoans are attached to a tree limb, and bivalves attached to a piece of rubber. Litter has become a transport mechanism for alien species.
• Figure 13. Newer construction south of Santa Veronica beach has ignored the lessons of the older village – don’t build next to the sea. Such buildings are not only threatened by wave erosion of the toe of the cliff, but also slumps and landslides due to over-steepened slope, ground-water seepage, and loading by the buildings and swimming pool.
• Figure 14. Another example lessons ignored and a house built too close to the back of the beach and threatened by storm-surge and wave attack. The sand-bag walls and driftwood fences will be of little protection in a big storm.
• Figure 15. This aerial view in the Salinas del Rey area is evidence of where the home owners want the beach line to be vs. where Nature will put the beach line. Note the houses in the foreground are fronted by walls with the back beach against the wall (sand over the wall in storms), but in the far back-ground note that the position of the beach is past the wall line, even with the houses, where it has not been restricted.
• Figure 16. A brief message in beach art.

---

References

• Anfuso, G., Rangel-Buitrago, N., Correa, I., 2015. Evolution of sandspits along the Caribbean Coast of Colombia: natural and human influences. In: Randazzo, G., Jackson, D., Cooper, J.A. (Eds.). Sand and Gravel Spits. Springer, New York, pp. 1-21.
• El Heraldo (Eliana Avendaño), 2019, Erosión costera también golpea a Juan de Acosta.
• El Tiempo (Leonardo Herrera Delgans), 2019, Santa Verónica lucha para que el mar no se trague sus playas.
• Gracia, A., Rangel-Buitrago, N., Florez, P., 2018. Beach litter and woody-debris colonizers on the Atlantico Department Caribbean coastline, Colombia. Mar. Poll. Bull. 128, 185-196.
• Neal, W.J., Bush, D.M., and Pilkey, O.H., 2017, Managed Retreat. In Finkl, C.W. and Makowski, C., editors, Encyclopedia of Coastal Science, 2nd Edition, Springer, Dordrecht, Netherlands, 7p. doi:10.1007/978-3-319-48657-4_201-2
• Rangel-Buitrago, N., and Neal, W.J., 2018,Coastal Erosion Management. In Finkl, C.W. and Makowski, C., editors, Encyclopedia of Coastal Science, 2nd Edition, Springer, Dordrecht, 15p.
• Rangel-Buitrago, N., Anfuso, G., Correa, I., Ergin, A., Williams, A.T., 2013. Assessing and managing scenery of the Caribbean Coast of Colombia. Tour. Manage. 35, 41-58.
• Rangel-Buitrago, N., Williams A., Anfuso, G., Arias, M., Gracia, A., 2017. Magnitudes, sources, and management of beach litter along the Atlantico Department coastline, Caribbean coast of Colombia. Ocean Coast. Manage. 138, 142-157.
• Rangel-Buitrago, N.G., Williams, A., Anfuso, G., 2018. Killing the goose with the golden eggs: Litter effects on scenic quality of the Caribbean coast of Colombia. Mar. Poll. Bull. 127, 22-38.

By Cecelia Dailey

The locals call it “lava beach”—a misnomer which leads some to believe the unique formation found here are igneous in origin. But these mystifying “black rocks” crumble to the touch, staining the hands, feeling gritty with sand. Although many are black, these “rocks” are sometimes light colored, deep red or burnt brown. Composed of ancient sand compacted by weight and time, the beach’s eroding cliff is hard enough to form cool little caves, draped with roots of vegetation struggling to survive above. The “black rocks” form promontories cracked with lines, pools, and rounded stones, being carved by waves on this northern Florida beach. Sometimes you can see sediment swirled together in the rock-like formations—evidence that once this material was deposited by water. Now, these layers below the maritime forest are exposed.

Morning fog lifts and a hazy sea breeze makes a beautiful, mysterious scene, a feeling impossible to fully capture on my recent return trip. It’s busy in January but easy to escape up the beach. As the deep black material disappears, white sand instead composes the beach, and overwashed areas create holes in the forest to rest. The plucked branches of stunted oaks make a patterned rhythm overhead, saw palmettos forming the forest floor, around my bed of washed up Spartina. Last fall, Hurricane Matthew hit with substantial force here and entire palmettos, still alive, and oaks with root balls as large as 20 feet are newly washed up. Out to sea, the silvery surfaces of those trees fallen long ago shine in the low morning sun.

A few years ago, in August, at low tide, I had to come to this beach for the first time, on a drive leaving Jacksonville—and found it a wonderful surprise. Weathered trees piled high, a beach full of secret hiding places. I would have recognized pluff mud, but the “black rocks” take on a different character—sandy and hard, not sticky and soft. Such depth of color stains as it crumbles. An almost rusty copper color seeps out from below the sand. FloridaHikes.com says the “rocks” are composed of compressed sand and decayed leaves. (1) Dr. Charles Finkl, who has studied Florida beaches extensively, describes the “rocks” as “weathered coastal sands” and not rock per se, but “partially indurated” or hardened sand. He says “The dark or black color is most likely due to reducing conditions when the sediment was flooded. It then became contaminated by organic materials, humus, manganese, and reduced iron. The lighter colored area or splotches are most likely oxidized organo-iron compounds.” Iron, depending on various conditions and compounds, can “range in color from black, olive, dark gray, red, to yellowish hues.”

“As the deep black material disappears, white sand instead composes the beach, and overwashed areas create holes in the forest to rest… ”
— Cecelia Dailey

Living with Florida’s Atlantic Beaches explains: “The muds and old tree roots contained in such deposits are from marshes and forests, indicating that this location was once the backside of the island. The shoreline (beach) retreated landward as it is doing now, and the island sand first buried the marsh mud and then the forest that grew in the soil as the island rolled over itself.” Clearly island migration is happening here, and if there is any doubt that island migration is a real phenomenon, this is the beach to study.

Fort George Inlet, shifting to the north, is free to roam on this undeveloped coastline. (2) There are 3 points of entry to Big Talbot Island’s trails allowing walking and biking. Parking is set about 1/2 mile behind the trails leading to the beach. Blackrock Trailhead is in the center of the island, where I explored.

Big Talbot Island is a protected state park, bordered by several more parks (with camping) including Little Talbot and Amelia Island. Timucua Ecological and Historical Preserve encompasses 46,000 acres behind the Talbot islands with artifacts of Native Americans including shell mounds, ruins of tabby slave houses and other structures, and a variety of habitats to explore including marsh, swamps and maritime forest.

A huge contrast to the urban areas of Jacksonville to the south and Amelia Island to the north, heavy with beachfront development, these parks prevent future development in this lowland adjacent to St Johns River, Fort George Inlet, and Nassau River. Highway A1A runs along the Florida coast starting at Fernandina beach and a ferry connects to Hanna Park, where I camped, a wonderful large city park right on the beach. A naval station, power plants, and industrial complexes line the St. Johns River on the way into Jacksonville.

The road coming in from I-95 toward Amelia Island in Nassau County has wide sidewalks and other road improvements, looking like they are getting prepared for growth. In fact, a 4,200 acre development project by TerraPointe LLC is part of the plan here. (3) In controversy, Fernandina Beach (on Amelia Island) is progressing toward approval for a 24 acre development that will fill wetlands. (4) Nearby Cumberland Island, GA—which gained national park status in 1972 to prevent any future development—is slated for 10 new homes on an 88 acre tract which carries “conservation preservation” zoning. (5)

Timucuan and nearby coastal parks including Big Talbot Island are examples that can be celebrated for their preservation of cultural and natural history, and prevention of development in sensitive coastal areas.

References

• 1. Black Rock Trail, Florida Hikes!, accessed 22 Jan. 2016.
• 2. Bush, Neal, Longo, Lindeman, Pilkey, Esteves, Congleton, Pilkey. Living with Florida’s Atlantic Beaches, Coastal Hazards from Amelia Island to Key West, Duke University Press, 2004.
• 3. Rayonier’s TerraPointe kicking off 4,200-acre project in Nassau County, Financial News and Daily Record, 7 Aug. 2013.
• 4. Thamme, Suanne Z. Development at 14th & Lime Streets moves a step closer, Fernandina Observer, 20 Oct. 2016.
• 5. Chapman, Dan. Planned new homes on Cumberland Island rattle environmentalists, The Atlanta Journal-Constitution, 9 Dec. 2016. http://www.myajc.com/news/state–regional-govt–politics/planned-new-homes-cumberland-island-rattle-environmentalists/CVIJpbyGSi3l4f5a9gtLSO/

Additional articles on nearby development…

• Thamm, Suanne Z. LignoTech Florida breaks ground for Fernandina Beach facility, Fernandina Observer, 18 Jan. 2017.
• Landers, Mary. Cumberland island property split approved, Savannah Now, 9 Dec. 2016. http://savannahnow.com/news/2016-12-09/cumberland-island-property-split-approved
• Jacksonville developers planning new homes on Amelia Island, Jacksonville Business Journal, 8 Apr. 2014. http://www.bizjournals.com/jacksonville/news/2014/04/08/jacksonville-developers-planning-new-homes-on.html
• Nicklas, Steve. North Florida Development Projects Signal Remarkable Turnaround Story, Amelia Island e-Magazine, 10 Oct. 2013.
• Turner, Kevin. Development on Crane Island May Happen Yet, The Florida-Times Union, 1 July 2010. http://jacksonville.com/business/2010-07-01/story/development-crane-island-may-happen-yet
• Tanner, Jane. Plans to Preserve a Black Beach Enclave in Florida, The New York Times, 24 Jan. 1999. http://www.nytimes.com/1999/01/24/realestate/plans-to-preserve-a-black-beach-enclave-in-florida.html

Many thanks to Dr. Charles Finkl and Dr. Orrin Pilkey for reviewing this article before publication and providing their remarks. Charles W. Finkl, Ph.D., CSci, CMarSci, FIMarEST, CPGS, CPSSc, PWS, M.ASCE is President & Executive Director of The Coastal Education & Research Foundation, Inc. (CERF), Editor-in-Chief of the Journal of Coastal Research (JCR), and Distinguished University Professor Emeritus, Charles E. Schmidt College of Science, Florida Atlantic University. Orrin H. Pilkey is James B. Duke Professor Emeritus of Earth Sciences, Nicholas School of the Environment, Duke University, and author of numerous texts including Lessons from the Sand (2016), Retreat from a Rising Sea (2016), The Last Beach (2014), The World’s Beaches (2011), Global Climate Change (2011), The Rising Sea (2009), Useless Arithmetic (2007), Atlantic Coast Beaches (2007), How to Read a North Carolina Beach (2004), A Celebration of the World’s Barrier Islands (2003), The Corps and the Shore (1996), The Beaches Are Moving (1983).

By Gary Griggs, Distinguished Professor of Earth and Planetary Sciences, Director Institute of Marine Sciences, University of California, Santa Cruz, California

The coast of California north of San Francisco is markedly different from the iconic southern California coast with its warm sunny beaches, palm trees, and intensive shoreline development. The topography and weather change as you cross the Golden Gate Bridge and steep coastal mountains replace the wide sandy beaches of Monterey Bay and southern California.

The geologic history of California’s north coast is evident in the typically steep relief and coastal landforms. This is an area where a drive along much of the narrow lanes of State Highway One along the often steep coast is always an adventure and where it’s never wise to take your eyes off the road for very long. Most of the beaches occur at the mouths of the coastal streams.

Scattered along the combined 255 miles of the mostly rugged coastlines of Mendocino, Sonoma and Marin counties are a handful of small towns and even smaller communities. Most of these have fewer than 1000 residents and some have less than 200. There is something unique about almost all of these towns – they are built on nearly flat, uplifted marine terraces that are common features along this coastline. Mendocino, Fort Bragg, Point Arena, Elk, Albion, Caspar, Inglenook and Westport are a few of these small communities. Without the flat terraces or benches, however, development would not have been possible and there wouldn’t have been a Highway One to allow people to drive along and experience this wild and scenic coast.

“Marine terraces are common along the U.S. west coast, particularly California and Oregon, but they are also common along many of the coasts facing the Pacific Ocean: Mexico, Central and South America, New Zealand, New Guinea and Japan… ”
— Gary Griggs

Marine terraces are common along the U.S. west coast, particularly California and Oregon, but they are also common along many of the coasts facing the Pacific Ocean: Mexico, Central and South America, New Zealand, New Guinea and Japan, for example. Some of these locations, such as the coast of northern California, may have just a single terrace, but others may have many more, like giant stair steps ascending the coastline. The Palos Verdes Peninsula near Los Angeles has 13 terraces and the offshore San Clemente Island has 25 individual steps or terraces.

Why are these flat terraces so common along the California coast? Creating and then preserving marine terraces requires several processes: 1) coastal bedrock that is soft enough to be eroded or worn down by waves in the intertidal surf zone; 2) an oscillating or fluctuating sea level; and 3) a slow but continuous uplift of the coastline.

Rocky terraces are forming today off of most coastlines due to continuous wave attack and these can be seen and explored at very low tides. Sea level has been rising and falling for millions of years in response to changing climate driven by variations in the amount of heat we get from the sun. Climate change is directly related to cyclical patterns in the Earth’s tilt and wobble on its axis of rotation, and also an irregular orbit around the sun, which brings us closer and take us further from the Sun over cycles of tens of thousands of years. As the Earth gets slightly closer to the Sun and warmer, ice melts and seawater expands, raising the level of the ocean. When the Earth gets farther away the opposite happens. As sea level rises and falls, the shoreline moves inland and then back offshore. The third requirement for terrace formation is a gradual uplift of the coastline, a result of California’s active tectonic or mountain building history.

Waves erode a terrace when sea level is high and the climate is warm. When the Earth cools, sea water evaporates and is transferred to continental ice sheets and glaciers. Sea level drops and we uncover this former underwater wave cut terrace. Meanwhile in the tens of thousands of years before sea level rises again with the next warming cycle, the coastline is uplifted a few tens of feet and we elevate and may preserve a marine terrace. This process has been repeated many times over the past several million years and one, several or many of these flat former sections of seafloor may now be preserved along the coastline above the reach of the waves. A hundred thousand years pass and early settler come along, find their way along the flat terrace and decide to cultivate the land and eventually built a town. Towns are built on the terraces, which otherwise wouldn’t have been possible, but for the combination of several geologic processes and a lot of time.