Lost Civilization

The Mediterranean stands out because it contains hundreds, if not thousands, of ancient submerged ruins. A few hundred represent the remains of Roman harbors, coastal towns and villages. Some sites reflect all archeological periods of the last 5,000 years, and several sites even go back farther. Why did the ancient people build so many coastal centers? Then how did those cities sink?

There were good reasons why the ancients built their cities and harbors so profusely on Mediterranean shores. With the nearby Red Sea and Arabian Gulf, the eastern Mediterranean emerged as one of the chief cradles of sea-faring commerce when Neolithic village communities evolved into trading Bronze Age powers about 3000 BC. When the Bronze Age began, the Mediterranean already abounded in anchorages produced by climatic change over the previous 15,000 years or so.

During the last Ice Age, when the sea level lay as much as 100 meters (330 feet) lower than now and the climate became locally wetter, rivers bordering the Mediterranean had cut deep valleys across what is now the continental shelf. As the sea rose to its present level, its waters invaded countless valleys and inlets. Thus, at the beginning of the Bronze Age, every coast became studded with perfect natural harbors.

However, this sailors’s heaven did not last long. As sea levels stabilized, the sea’s erosive force and sediments supplied by the rivers and winds between them began to straighten coastlines. The process happened faster to a gently shelving coast with small indentations than to a steep, deeply indented one.

Mediterranean coasts are unequal in these respects. The southern and eastern shores turn out the straightest and have the fewest inshore and offshore islands. They also lack big rivers except for the Nile. But they do have hundreds of intermittent streams bringing down plenty of sediment, especially sand from the Sahara and other deserts. Today, therefore, you can find few good harbors from Tangier to Beirut.

On the contrary, the northern Mediterranean shore, from Gibraltar to Turkey, varies from stretch to stretch. In general, they appear steeper and more deeply indented than the southern and eastern shore. Many sizable rivers of southern Europe and Asia Minor enter the sea along this coast. The continental shelf appears narrow so that most sediments washed in by these rivers plunge into deep water, or build only small deltas. Unlike the low southern coasts, the northern coasts have changed little since Bronze Age times, and still retain deep bays, steep headlands, and numerous islands. In many coastal sites, local erosion or silting has been too slight to altar the topography. The major exceptions are on the Rhône, Po, and Menderes deltas, where the coastline has advanced many kilometers in the last few thousand years.

These coastline changes, however, don’t explain how scores of Bronze Age and later sites became drowned. By the beginning of the Bronze Age the rise in sea level that had followed the end of the last Ice Age glaciation has just about stopped, and the level has fluctuated little since since. Indeed, the average Mediterranean sea level relative to coastal land has varied by no more than plus or minus half a meter in the last 5,000 years.

But this gives you only the general picture. Some parts of the coast have been sharply uplifted and others depressed. A number of harbors have collapsed almost intact into the water in Italy, Greece, Turkey, and Cyprus. We must take a close look at the forces that make much of the Mediterranean coast so unstable—the same forces that help to give the north and south coasts their different characters. These forces turn out the massive earth movements explained by the theory of plate tectonics.

This theory holds that Africa, together with part of the floor of the Mediterranean, keeps moving north toward Europe at about 2.5 centimeters (an inch) a year. As smaller continental fragments, Arabia and Turkey move in other directions. Over many million years, Corsica, Sardinia, and Italy have rotated counterclockwise and swung away from France, opening up the Tyrrhenian Sea and narrowing the Adriatic. At the same time, the eastern floor of the Mediterranean has been compressed and foreshortened.

As shown in the above map, areas of maximum convergence and subduction concentrate on the vicinities of Sicily, Greece and Crete as well as the southern coast of Turkey and the western coast of Cyprus. And you can see a number of volcanoes along these plate boundaries. Even in the short span of time since civilization began, earth movements have sparked off volcanic eruptions and also earthquakes that have moved some stretches of coast up, down, or both.

Among the most famous is the eruption of Mount Vesuvius that took place in A.D. 79. It produced powerful convecting plumes of ash ascending up to 45 kilometers into the strato­sphere.

Pliny the Younger, a Roman statesman, wrote a remarkable account of the eruption, describ­ing the devastating rupture that killed thousands of people and buried the towns of Pompeii and Herculaneum under huge volumes of tephra (deadly pyroclastic flows) and massive lahars (volcanic mud flows). During the eruption died Pliny’s uncle—Caius Plinius (Pliny the Elder), a respected naturalist and Admiral in the Roman navy. To properly record the circumstances of his esteemed uncle’s death, Pliny the Younger wrote two letters to the historian Tactius describing the eruption of Mount Vesuvius.

Surprisingly, however, Pompeii laid buried for over 1,700 years until it was rediscovered by accident during the excavation of a water line. Uncovering the remains of Pompeii provided a unique understanding of the lives of ordinary people during Roman times.

Mount Vesuvius has experienced numerous eruptions since A.D. 79. Many of these are depicted in paintings, lithographs, and engravings. The eruptions of the Vesuvian type generate large eruptive columns that are powered upward partly by the thrust of expanding gases, and by convective forces with exit velocities of several hundred meters per second. Some reach heights of 45 km. These eruptive columns produce widespread dispersals of tephra that cover large areas with thick layers of pumice and ash deposits. In general, the accumulation of pyroclastic fall appears asymmetric around the volcano as the eruptive column turns into the direction of the prevailing wind.

The eruptions like Mount Vesuvius are not only subject to large volumes of pumice fallout but they are also subject to the most dangerous types of volcanic phenomena: pyro­clastic flows and lahars. The occasional collapse of the eruptive column will generate hot, pyroclastic flows that advance down the volcano flanks at hurricane-force speeds. In addition, large volumes of water are often generated by the melting of snow banks and alpine glaciers during the eruption. The mixing of this water with unconsolidated tephra can generate volcanic mud flows (lahars), which look like flows of wet concrete, but advance down slopes as fast as a rapid stream.

Those devastating flows buried Pompeii, located to the southeast, on the downwind side of the volcano. Not only did it receive the destructive force of several pyroclastic flows, but it also went under a huge layer of airfall tephra.

A house damaged by the earthquake (Magnitude 6.6) that took place on May 13, 1995 in Grevena, north­western Greece.

As you would expect, the regions of fastest relative plate movements turn out the regions where earthquakes happen most often. Thus the coasts of Algeria, Italy, Greece, the Aegean, Malta, Crete, Cyprus, Lebanon, and Israel are much more unstable than others.

Less known is one of those earthquakes that might have ruined the ancient civilization in Malta, which sided with one of the most active plate boundaries—the one between North Africa and Sicily.

Beginning in 5000 BC, seven distinct ages of man on Malta went through 7,000 years. Each age produced the innumerable kinds of structures and handiworks. The Neolithic, the Copper Age and the Bronze Ages have been identified and described by leading archeologists since the first part of the twentieth century, and in recent years, they have been able to classify them precisely.

The cave dwellings, which symbolize the Neolithic Period from 5000 to 4000 BC were sought out by these first inhabitants of Malta and Gozo, but in due course they built villages of rubble huts, as did other prehistoric peoples who lived initially in cave dwellings thereafter.

The magnificent megalithic temples were built by the Copper Age people who followed the Neolithic people and lived on the islands for a millennium and a half until they disappeared suddenly and entirely except for a small remnant that later lost its identity. What on earth happened to them?

The temple at Tas-Silg turns out the only one of the three dozen or more Copper Age temples. It continued in use as a complete structure after the catastrophic end of that age about 2400 BC. The archeologists believed that this temple survived because its oval shape may have made it more sturdy. Hence, it survived many devastating earthquakes. It appears that a small community of Copper Age people remained there, while all the rest apparently disappeared completely.

To Part 2
(Malta—lost Atlantis ??)