they can be moraines seems impossible; it is difficult to understand how they can have been deposited either by currents in a sea or by the direct action of rivers; in short, the exact mode in which they have been formed, as already stated, is one of the unsolved problems in geology.

CHAPTER III

ICE-WORK IN EUROPE AND OTHER PARTS OF THE WORLD

THERE can be no doubt that Scandinavia, during parts at least of the Glacial Epoch, was almost buried beneath ice, but it is less certain how far southward this extended. Drifts, however, in some way of glacial origin, can be traced, speaking in general terms, to the fifty-first parallel of latitude. Some of

1

the most remarkable sections occur in the island of Möen, displayed in cliffs from 100 to 400 feet high. The chalk-like that of Norfolk-is overlain by the following deposits:-(1.) Stratified loam and sand (about 5 feet thick), containing occasionally marine shells, sometimes having a breccia of flint at the base. (2.) Unstratified blue clay, with small pebbles and fragments of Scandinavian rocks—20 feet. (3.) Unstratified yellow and more sandy clay, with pebbles and boulders (angular) from the same source--40 feet. (4.) Stratified sand and gravel, with occasional large erratics; this varies in thick

1 Described by Sir C. Lyell, "Antiquity of Man," chap. xvii. See also Professor J. Geikie, "Prehistoric Europe," chap. x.

ness from 40 to 100 feet, but is local in occurrence. Here and there the Chalk and the Drift appear to have been faulted and folded together in a remarkable fashion, and to have been subsequently much denuded.

1

Boulder clays occur abundantly, though commonly they are not well exposed, in Denmark, Holstein, and Northern Germany. They contain erratics of chalk, rivalling in size those of Cromer. Those in Mecklenburg-Schwerin are so large as to have been mistaken for rock in situ; but they are underlain by clay, and sometimes more than one such mass has been pierced in a boring.

Farther south, as in Halle in Saxony, deposits of brown coal (Tertiary age) are curiously mixed up with the boulder clay. This, in many districts, is parted by beds of sand or gravel, and at Potsdam at least three masses of it can thus be distinguished. In clays and sands alike, as far south as this place, marine shells can be found, sometimes also those inhabiting fresh water.2 In fact the glacial deposits

1 Some are of opinion that the Chalk near Trimingham (Norfolk) has been similarly bent up. I am, however, doubtful whether the mass is in situ. Certain geologists maintain that these disturbances are due to the uprooting and thrusting powers of an ice-sheet; but it remains to be proved, not only whether an ice-sheet ever reached either locality, but also whether ice under any circumstances can produce such effects. The hypothesis accordingly must be ranked among those which are possible, but at present are unsupported by much evidence.

The clay is often extremely tough. It has been noticed that in Saxony, while most of the fragments both in it and the gravel have obviously come from the north, some undoubtedly have been derived from the opposite direction.

of this part of Europe seem to bear a considerable resemblance to those of England. The underlying rock is sometimes broken up, sometimes smoothed and striated, as is the case with the Muschelkalk near Berlin. Ice-worn or striated surfaces are said to have been observed near Wurzen in Saxony, near Halle and Leipzig, on the Rainsdorferberg, and on the Pfarrberg.

Indications of glaciers have been recognised, with more or less certainty, in the higher parts of the Black Forest and the Vosges, and well - marked moraines exist in some parts of the Carpathians, as in the valleys of Biaty Dunajee and of the Theiss. In the latter, though the surrounding summits do not exceed 6800 feet above the sea, the glacier is said to have been forty-five miles long, and till with striated stones to occur as low down as 1800 feet.

Glaciers formerly existed in Central France, though. it is difficult to determine their exact limits. They radiated from the Puy de Sancy, and near Issoire a til has been described which is parted into three masses by gravel beds. It contains angular blocks, sometimes striated, which are often a cubic metre in volume, and occasionally even 6000 cubic metres. These have come from the Mont Dore dis1 For this and the next paragraph compare the map opposite to page 35.

2 It has been asserted that small glaciers existed in Brittany; but this appears hardly probable. Erratics, however, have been noticed, which seem indicative of some form of ice-action. (Ann. Soc. Géol. du Nord, 1878.)