The former presence of glaciers at nearly the same altitude has also been proved by the travels of Mr. Gifford Palgrave in Anatolia,[256] especially in the valley through which the Chorok flows, and in the mountainous country to the north-east, between Georgia and the Black Sea. The river Chorok runs about 120 miles in a north-easterly direction, and is separated from the Euxine by a mountain chain reaching a height of 11,000 feet, thus forming a long strip of land, which is called Lazistan after its inhabitants, a tribe of Lazes. It then turns suddenly to the north, where it falls into the sea. The southern side is determined by mountains of Cretaceous, Jurassic, and Plutonic rocks, which form the watershed between the tributaries of the Black Sea and Persian Gulf. Three large moraines are to be found on the southern side of the valley, their lower extremity about 5,000, their upper origin nearly 8,000 feet above the sea. No moraines are seen where the chain does not reach an altitude of 7,000 feet, though angular boulders are not uncommon. The upper mountain contours are invariably rounded, and smoothed off, and the sides are scooped too widely for the depressions to have been caused by water. Low down in the valley the slopes terminate in rifted precipices.
That these moraines were posterior to the volcanic eruptions in the district, is evident from the examination of a broad stone ridge, near the highest point to the east of Erzeroum, where at a height of 7,000 feet the Jurassic limestone was interrupted by a volcanic outbreak of several miles in extent. Traces of a crater were visible. Above, the granite peaks rose to a height of 9,000 feet; below, a wide moraine crossed the road, composed of volcanic fragments mixed with granite. Consequently, it must have been formed after the volcano had become extinct. Similar traces are to be found at Keskeem Boughaz. Mr. Palgrave concludes “that the ice-cap of the north-eastern Anatolian watershed, in post-pleiocene (pleistocene) times, must have reached downwards, on the northern side of the range, to 7,000 feet above the present sea-level, while some of the glaciers issuing from it descended to about 4,500 of the same measurement.” Striated and ice-worn boulders, especially of granite, were very abundant. This region, it must be observed, is within sight of the lofty granite range of Tortoom, which is “streaked with perpetual snow.”
After leaving the Chorok valley and getting on to the watershed, at a distance of fifty miles to the north-east, Mr. Palgrave reached the main ridge or backbone of the land. Here, among the limestone ledges, about 6,400 feet above the sea, is a colossal moraine, formed of worn granite blocks, partly overgrown with forest, and descending from a height of over 8,000 feet. It is divided, by a valley, from a lofty undulating granite plateau that is scooped out here and there into deep oval lakes, always full of blue water. The sides of the plateau are strewn with boulders of granite, brought from the higher peaks about five miles off. These boulders occur in greater or less abundance down to the basin of the Ardahan, near the sources of the Kur or Cyras, which joins the Araxes before flowing into the Caspian. The height of this Ardahan basin is about 6,500 feet; it is, but for a slight easterly slope, a water level. The bottom consists of deep alluvial soil mixed with detritus and boulders; the sides are rounded and smoothed, and bear every mark of long ice-covering. These plateaux, studded with lakes, stretch east to Russo-Georgia, till their greatest height is gained at Kel Dagh, a mountain about 11,000 feet high: thence they descend to the plains of Georgia and the Black Sea.
No glacial marks have been observed on the seaward side of the range, except at Hamshun in the Lazistan mountains, between the River Riom and Trebizond. Here, at 6,900 feet, is a granite-strewn plateau, thinly green with grass, sheltered from the sea by lofty peaks on the north-west, and backed to the south-east by tremendous jagged granite cliffs, the highest 12,500 feet above the sea. The plateau itself is about forty miles in length, irregular in breadth, its surface rounded and jotted over with boulders. But just as my track led near under the base of Verehembek, at an altitude of 8,300 feet, it crossed a large broad moraine, descending from the higher slopes, and having its base in a broad bare valley not far below, which showed that here, at the highest and widest part of the Lazistan chain, perpetual ice had once existed in sufficient quantity to furnish at least one glacier. From this case it seems that the limited ice-cap of the Hamshun highlands extended no further down than 8,500 or 9,000 feet, thus differing by a line of from 1,000 to 2,000 feet from the glacial covering of the inland range.
The Glaciers of the Atlas Mountains.
Similar traces of glaciers have been observed in the Atlas mountains by Mr. George Maw,[257] in his travels in Morocco with Dr. Hooker and Mr. Ball in 1871. “After four hours’ continued ascent,” he writes (p. 19), “the termination of the glen comes into full view, and we observe with great interest that it is closed by a group of moraines, proving the former existence of glaciers in the Atlas, and confirming my opinion that the great boulder beds flanking the chain are also of glacial origin. Two villages, probably the highest in the Atlas, are built on the principal moraine; Eitmasan, at its base, at a height of 6,000 feet, and Arroond, near its summit, at a height of 6,800 feet; the terminal angle of the larger moraine having a vertical height of 800 feet. It is composed of immense blocks of porphyry, lying at a steep angle of repose, up which it takes us nearly an hour to climb. The existence of these moraines in latitude 30½° N. (the latitude of Alexandria) is perhaps the most interesting fact we noticed during our journey, for this is the most southerly point at which the evidence of extinct glaciers has been observed, and tends to confirm the opinion entertained by many geologists, that the refrigeration during the glacial period was almost Universal.”
Glaciers probably the result of elevation above the Sea.
The elevation of the African moraines above the sea, of about 6,000 feet and upwards, is nearly the same as those of Asia Minor. If the mountains of the Atlas, Lazistan, and Lebanon shared in the upward movement of the Mediterranean area, the addition of 3,000 feet to the height could not fail to leave marks behind of the low temperature thereby caused. It is very probable, that during the time the Mediterranean was reduced to two land-locked seas, these mountains were covered with snow-fields, and constituted the ice-sheds of glaciers.
From the range of the mammalia we have inferred the existence of land barriers, extending across from Africa to Spain and Italy, and from Candia to Greece, and their actual existence beneath the sea has been proved by soundings, which necessitate an elevation of from 400 to 500 fathoms to bring them above the sea-level. We have also seen that the higher mountains, which most probably participated in this upward movement, bear traces of a lower temperature in the moraines of the Atlas and Lazistan. The hypothesis of such an elevation during the pleistocene age may therefore be taken to be proved so far as it explains two widely different classes of facts, the distribution of the mammals and the existence of glaciers where they are now unknown.
The physical condition of the Mediterranean area, in the pleistocene age, may be summed up as follows. The mainland of Africa extended northwards to join Europe, in the direction of Gibraltar and Italy. The islands of Malta and Sicily were hilly plateaux, overlooking an undulatory plain. Corsica and Sardinia were joined to Italy, Majorca and Minorca to Spain, Candia to Peloponese, and Cyprus to Asia Minor. The area now occupied by the Adriatic Sea constituted the lower valley of the Po, and the Archipelago was a plain studded with volcanic cones; and at the same time glaciers crowned the higher mountains of northern Africa and of Asia Minor.