The Mediterranean

How Geologic History Shaped Human History

-or-

How Blue Water Sparkles Beautifully

Sattelite photograph depicting the Rock of Gibraltar. Note how the ocean-ward coasts seem smooth and regular compared to those east of the Rock.

Geologic History

This page focuses generally on a few processes of particular significance. I will examine, therfore, the general geologic history of the Mediterranean; that established, I will examine a couple of contemporary processes that either maintain or jeopardize our ephemeral paradise.

To get started on a general background, here is a graphic history of Mediterranean tectonics, from the Miocene to the late Triassic. These maps show the dissappearance of the Tethys Ocean, ancient predecessor to the Mediterranean.

During the Mesozoic, several processes contributed to the creation of the Mediterranean. Sea-floor spreading was occuring in the young Atlantic, pushing the North American plate away from the Eurasian and African plates. The Tethys ocean, "a great sea-way...that formed a continuous passageway between the Indo-Pacific and the Atlantic,(Ciesielski 2002)" also exhibited spreading, pushing the Eurasian plate away from the African plate in the East, and pushing them together in the West, causing subduction.. Then the Tethys bagan to converge, pulling the two continents back into alignment and allowing spreading to occur in the infant Mediterranean. (Kolker 2003)

The more recent Cenozoic has been tumultuous as well. Most famous of these calamities occured when the Mediterranean found itself isolated from the Atlantic due to the Gibraltar sill's high wall, which tectonic compression had raised above sea level. The Mediterranean is constantly refilled by the Atlantic; if it were not for this the evaporation rate of the region would eliminate the entire body of water(Ciesielski 2002) . Much of the sea did dry up, laeving, for quite some time, a desolate salt basin (Kolker 2003).

This condition, occasionally watered by rivers and small Atlantic spills, persisted until the Pliocene. Sea levels rose, and the ferocity of local tectonics cooled. Atlantic waters flowed over the now complacent Gibraltar, restoring the Mediterranean's marine identity(Kolker 2003).

Thanks to Professor Ron Blakely and his surprisingly thorough online database: http://jan.ucc.nau.edu/~rcb7/RCB.html

Modern Processes

The African plate is still pushing northward, causing subduction beneath the countries with southern coasts (Ciesielski 2002). Many of the northen countries are known for their mountains, a result of this continuing process. The situation is not quite so simple, however; there are many points of convergence and subduction throughout the modern Mediterranean, making it a distinctly geologically active region.

In the last few centuries, a geological blink, humankind has done much to alter Mediterranean geology. We have built rdiculous strucures all along the coastlines, exacerbating and rerouting erosional patterns. We now travel the Sea in pollution-producing boats that unbalance the natural chemical ratios of the region. We have mismanaged beaches and exploited local resources, once again speeding along or confounding natural processes. To top it all off, we have actually altered the geography by building dams and canals (Marbena 2003). The perfect little Sea that geology gave Western history is, in many ways, in great jeopardy.

Volcanoes of the Mediterranean

Though volcanoes are not the focus of this page, they are ubiquitous enough an occurrence in the Mediterranean to merit mention. The constant tectonic activity that has plagued the Sea from its birth to the present has also riddled its domain with volcanic activity.

Volcanoes of Greece

Volcanoes of Italy

More sattelite images of the Mediterranean. on the far left is an excellent shot of the Greek island Crete, once the kingdom of Minos and his labyrinth-bound minotaur.

Introduction

What is now dubbed the Mediterranean (literally, "middle earth") is an area with a complex and fascinating geologic, and, much later, social history. Indeed, a variety of historical circumstances have created the unique geological characteristics that are typical of the modern Mediterranean.

To Westerners, the Mediterranean is of particular importance. In hallowed antiquity it was the ancient homeland of the clever Greeks, the play-place of the enigmatic Egyptians, the greatest road to Rome. The grave and glorious epics of Western society were composed here; indeed, two of our most exalted epics, Homer's Odyssey and Virgil's Aeneid, focus specifically on a hero's trans-Mediterranean journey.

The Mediterranean of Homer and Virgil is more or less the Mediterranean of today. Geologically, a few millenia is as the snap of a finger. The history of the geologic phenomena itself stretches back across millions of years, comprising in its own way an epic journey to become what we and the epic masters, in our modern age, see as an astonishingly beautiful testament to the Earth's capacity to provide for its inhabitants.

This map of the area illustrates the general topography of the region, the modern result of geologic processes.

Literature Cited

[my comrades in the class struggle also endeavour to enlighten]

Copyright © 20031 Earlham College. Revised 25 February 2003. Send corrections or comments to either the author, kiefegr@earlham.edu, or to professor, parkero@earlham.edu