Page:Quarterly Journal of the Geological Society of London, vol. 33.djvu/625

Rh

The Acropolis and part of the town walls of Heraclea stood upon the crest and slopes of a bold and almost isolated hill rising from the east side of the bay, formed by the promontory of land to the north-west of it, now called Cape Baba, but anciently the Acherusian Peninsula by Xenophon; for this city was the place from which he embarked for Greece, with his army, after his celebrated retreat.

The summit of this hill (Acropolis) consists of a capping of reddish indurated shale, a few feet only in thickness, and overlying stratified beds of tuffs, greenstone, volcanic mud, and trachyte conglomerates, by the outburst of which the reddish shales were evidently uplifted and altered in their colour and character; but Mr. Poole calls it sandstone, no doubt from a too hasty examination.

A portion of the same altered shales, or rather marls, appears also at the base of the Acropolis, near the shore, on its west side—likewise to the north and eastward of it, with the lavas intermediate.

A valley to the south of the Acropolis, in which is a large part of the modern town of Erekli, separates it from another hill over the coast, which is composed of whitish and grey marls, belonging, no doubt, to the same group as the indurated stratum capping the Acropolis, and the altered marls existing at its base.

These white and grey marls dip to the south-west at an angle of 30°, except on the east side of the hill, near the large burying- ground at its base, where they are nearly vertical, and where they are much discoloured and decomposed through contact with the trachyte conglomerates and stratified lavas which have burst out beneath them.

The age of these marls I was not able to ascertain, as the only fossil obtained from them was an oyster, too friable, however, to be preserved, but sufficient to show that they were of marine origin. From the form of the oyster I was disposed to consider the deposit to be of Miocene, or perhaps an earlier age.

In the promontory to the north and north-west of Erekli the volcanic productions of tuffs, trachytes, and basaltic conglomerates prevailed, having in some parts both uplifted and also overflowed the marine marls.

It is perhaps worth noticing, in concluding these remarks upon the volcanic character of the locality, that the ancients must evidently have recognized the plutonic or igneous origin of these lava-beds, notwithstanding their general stratified condition; for Xenophon states that a cavern was shown in the Acherusian Peninsula that led to the gates of Hades, and from which Hercules drew forth Cerberus, the guardian of its portals.

Strabo says it lay to the north of the town, and was two stadia deep; but I could hear of no such cavern in the neighbourhood. Yet it is possible that some traces of an extinct crater or volcanic vent may exist here, where, as I have shown, lavas and beds of