I have called special attention to these Irish lacustrine beds, because it is highly probable that the post-glacial age of similar alluvia occurring in many other places in these islands has hitherto been assumed and not proved. Now that we know, however, that a long interglacial stage succeeded the disappearance of the last general _mer de glace_, we may feel sure that the older alluvia of our Lowland districts cannot belong exclusively to post-glacial times. The local ice-sheets and great glaciers of our "third" glacial epoch were confined to our mountain-regions; and in the Lowlands, therefore, which were not invaded, we ought to have the lacustrine and fluviatile accumulations of the preceding interglacial stage. A fresh interest now attaches to our older alluvia, which must be carefully re-examined in the new light thus thrown upon them. Turning next to the Alpine Lands of central Europe, we find that geologists there have for many years recognised two glacial epochs. Hence, like their _confrères_ in northern Europe, they speak of "first" and "second" glacial epochs.[CI] Within recent years, however, Professor Penck has shown that the Alps have experienced at least three separate periods of glaciation. He describes three distinct ground-moraines, with associated river-terraces and interglacial deposits in the valleys of the Bavarian Alps, and his observations have been confirmed by Professor Brückner and Dr. Böhm.[CJ] The same glacialists, I understand, have nearly completed an elaborate survey of the eastern Alps, of which they intend shortly to publish an extended account. The results obtained by them are very interesting, and fully bear out the conclusions already arrived at from their exploration of the Bavarian Alps.[CK] A similar succession of glacial epochs has quite recently been determined by Dr. Du Pasquier in north Switzerland.[CL] Nor is this kind of evidence confined to the north side of the Alps. On the shores of Lake Garda, between Salò and Brescia, three ground-moraines, separated by interglacial accumulations, are seen in section. The interglacial deposits consist chiefly of loams--the result of sub-aërial weathering--and attain a considerable thickness. From this Penck infers that the time which has elapsed since the latest glaciation is less than that required for the accumulation of either of the two interglacial series--a conclusion which, he says, is borne out by similar observations in other parts of the Alpine region.[CM] [CI] Morlot: _Bulletin de la Soc. Vaud. d. Sciences nat._, 1854, 1858, 1860. Deicke: _Bericht. d. St. Gall. naturf. ges._, 1858. Heer: _Urwelt der Schweiz._ Mühlberg: _Festschrift d. aarg. naturf. Ges. z. Feier ihrer 500 Sitz._, 1869. Rothpletz: _Denkschr. d. schweizer. Ges. f. d. ges. Naturwissensch._, Bd. xxviii., 1881. Wettstein: _Geologie v. Zurich u. Umgebung_, 1885. Baltzer: _Mitteil. d. naturf. Ges. Bern_, 1887. Renevier: _Bull. de la Soc. helvèt. d. Sciences nat._, 1887.