ridge across it, and thus forms a lake or large tarn. In the north of England, and particularly in Scotland and central Ireland, the glacial rubbish-heaps have been sorted and re-arranged by the waves of the sea, since they were originally formed; for we know that the larger area of Great Britain was submerged to as much as 1,200 feet at the close of the Glacial period. The names of "Kaimes" and "Eskers" are given to these re-arranged rubbishheaps. They frequently form very wild and weirdlooking scenery, for the rubbish-heaps wind like serpents over the valleys and plains, or at the feet of the hills; and in Ireland and Scotland superstitious tradition has many a story to tell of the origin of such peculiar features in the landscape.

How softly and gently the ice left the hilly regions it once covered is indicated by the millions of loose stones or boulders, some of them of very great size, which are strewn over the surfaces of the gentler slopes of the mountains, or on the heights of the lower hills beneath. There they occur as "perched blocks," sometimes so delicately poised that they can be easily moved by the hand. If you examine them you see these boulders are usually formed of a different material to the rocks on which they rest. They are frequently perched in the most grotesque and impossible of positions; and it needs little observation to perceive that these boulders could not have been detached from above, and rolled down to their present positions, for such an impetus would inevitably have carried them below, where even now it seems as if a child could push them. But when we

know that ice-sheets once covered all the ground where these boulders are now seen, and that the moving ice-sheet must have had its surface strewn with detached blocks, which would be quietly let down when the ice melted, we have at once an explanation of the peculiar carrying agent which has placed them in their present positions. The low-lying parts and rounded terraces of such places as the Pass of Llanberis are crowded with perched blocks, some of them reposing in the most precarious situations. They are noticeable objects throughout all the hill and mountain scenery of Great Britain. Wordsworth refers to them, as he does in his "Prelude" and "Excursion" to many other features in the landscape of the Lake district, which the geologist knows were produced mainly by the powerful icetools in operation during the period we have referred to,

"As a huge stone is sometimes seen to lie
Couched on the bald top of an eminence,
Wonder to all who do the same espy.

By what means it could thither come, and whence,
So that it seems a thing endued with sense,
Like a sea-beast crawled forth, that on a shelf
Of rock or sand reposeth-there to sun itself."

The amount of wear-and-tear due to weather action, which has taken place since the mechanical action of ice gave its last finishing touches to the scenery of our landscapes, is best seen in the "Cheese-wrings," &c., of Derbyshire. The reason these are so much more abundant in Devon and Cornwall than among the mountains of Wales, Cumberland, Scotland, and

Ireland, is because Devon and Cornwall were left uninfluenced by the ice-sheet which in the other localities was so active. We have little or no evidence of glacial action in South Devonshire and Cornwall; neither is there any proof of those areas having been submerged when North Britain was last under the sea. The consequence is that the hills of Cornwall and Devonshire have been longer exposed to the kind of weather-action that is now going on than any parts of England, and the results are seen in those piles of rounded stones which represent the slow weathering that has removed from extensive areas the strata of which they are the dwindled representatives.

The Rev. J. Clifton-Ward, in his "Geology of Cumberland," recently published as one of the "Memoria" of the Geological Survey, gives an outline of the conditions which affected the Cumberland mountains during the Glacial epoch as follows:-"At the commencement of the cold period small glaciers occupied the heads of the various valleys, and as the cold continued and increased they became larger and larger, until, in many cases, they united, overlapping the lower ridges parting valley from valley, and forming one great confluent ice-sheet, the movement of which was determined to the north and to the south, or east and west-as the case might be, in different parts of the district-by the main waterparting lines. A great quantity of rocky débris was moved onwards and left scattered over the country, partly by the first-formed moraines being pushed forward, and partly by the ice overriding the same and dragging on and triturating the fragments be

neath it. In this way the Till was formed, sometimes left in rock-sheltered upland hollows, but most largely deposited on the lower and less inclined ground.

"Whether this first land-glaciation was interrupted by one or more mild periods, the deposits in this district do not prove. As the final close of this epoch of intense glaciation drew on, moraines were left by the retreating glaciers plentifully scattered in every valley, but the glacial streams and rivers must have made much havoc amongst them, cutting them up and bearing away their material to lower levels.

"Then, when the cold had disappeared, began a submergence of the district to a very considerable extent. As the land sank, the old moraine material was sifted, sorted, and partly rounded. At the ends of some of the fiords or straits, sand-bars were formed; but, as there was no floating-ice during the earlier stages of submergence, these sand and gravel deposits enclosed no large boulders. The district became gradually converted into an archipelago, and currents circulated among the islands. When depression had gone on to the amount of 1,000 feet or less, the cold returned, and ice-rafts bore blocks from one part to another. In many cases the direction in which currents swept the floating-ice was the same as that of the old glaciers, and thus boulders were transported along the same course at different periods and by different means. Sometimes, however, or at certain parts, marine currents bore floating ice, with its boulders, in directions opposed to, or much at variance with, the old glacier courses. Thus, when the land stood about 1,200 feet lower than at present, a

current, sweeping the north-western outskirts of the district, carried boulders from Sale Fell southwards on to Broom Fell. Not until the submergence reached over 1,500 feet was there any direct communication between the northern and southern halves of the Lake District, except by the straits of Dunmail Raise. Under such conditions a current very probably ran through those straits from south to north, turning mainly to the east on reaching Keswick Vale, though probably sending a branch off to the west; while other currents may have set through the straits between Skiddaw and Blencathra. The case mentioned of an ash boulder at the upper sources of the Caldew would seem to point to a current having at one time passed from south to north, up the Glenderaterra Valley and down through that of the Caldew. The block could not have reached its present situation from any of the volcanic deposits lying north of Carrock and Comb Height, and is scarcely likely to have come from the very limited ash exposures of Eycott Hill, to the south-east of the Caldew at Mosedale. It is not likely that this boulder could have been transported by glacier-ice or any form of ice-sheet, because it is in the very midst of lofty mountains which would have produced sufficient ice to have filled the valleys between them and kept out any ice-sheet foreign to this group. Hence, I am inclined to consider this case as a proof of submergence to the height of at least 1,300 feet, and of the existence of marine currents passing through the Skiddaw mountain group.

"The submergence continued until the land must