Near rising to a height of 1760 feet above the sea. Shap it may be seen between the limestone and the slates. It is supposed to have been deposited after the slate rocks had attained solidity, and had been scooped into deep valleys. Although it now occupies only a small area in the Lake District, it probably was at one time much more extensively spread, and was afterwards washed away by ocean currents. Mountain Limestone.-Above the old red sandstone is the mountain limestone, which almost encircles the whole of the Lake District. According to Professor Sedgwick, "It requires little effort of imagination to conceive that all the great patches of limestone, now marked on this part of our geological maps, were once united." It stretches from Egremont, past Cleator, Cockermouth, Caldbeck, Greystoke, and Shap, to Kirkby Lonsdale, and Kendal. In the S. of the district it embraces the heights of Underbarrow, Whitbarrow, and Witherslack. By the sea-coast at Grange it forms beautiful cliffs and terraces, and crosses over the Leven Sands to Dalton-in-Furness. A small patch lies on the opposite side of the Duddon Sands, close to Holborn Hill. Fewer mineral veins are found in the mountain limestone surrounding the lakes than in the same rock in other parts of Britain; but this is amply compensated for by the rich deposit of iron ore (hæmatite) which is found in the fissures and hollows of the limestone at Cleator, near Egremont, and near Dalton and Ulverston in Furness. The geologist who has entered the limestone caverns of Yorkshire and Derbyshire, and there observed the formation of the stalagmites and stalactites, will have no difficulty in accounting for the deposit of the "kidney ore." In all probability the new red sandstone covered the limestone, and the waters of the sea, saturated with red oxide of iron, filtered through the fissures and caves of the limestone and filled them gradually with metallic matter held in partial solution. The reader will remember that in a previous page it was stated that the same kind of ore is found near the tops of the highest mountains, from which it was inferred that the sandstone had at one time covered the whole district. Coal. The coal formation rests on the mountain limestone, and stretches along the W. coast from Whitehaven to beyond Maryport. At Whitehaven the mines extend far beneath the sea. The whole deposit once consisted of alternations of sand and finely-laminated mud, with countless fragments of drifted vegetable, sometimes single, sometimes matted together in thick and widely-extended beds. Occasionally the plants are upright in posture, and so entire that they seem not to have been drifted from the spots on which they grew; in such cases the coal-beds become the indications of forests and bogs submerged in bygone ages during the changes of level between land and water. In course of time the drifted sand-beds became sandstone; the mud became slaty clay or shale; the vegetable fossils were bituminized; and the whole formation passed into the condition in which we now see it. In the upper part of this group (as exhibited in different parts of the North of England) there are no marine remains; but it contains some beds of shells belonging to fresh-water genera. All the plants are of extinct species; many of them of extinct genera; and they are of forms which indicate a high tropical temperature. Among them are coniferous trees, like those in some of the South Sea Islands; gigantic reeds; tree ferns; enormous creeping plants with sharp pinnated leaves (Stigmaria); trees with fluted stems; and many other strange but beautiful forms of vegetable life, seemingly pushed to rankness and luxuriance by great heat and moisture. It is in vain to speculate on the exact duration of the carboniferous epoch; but we are sure that it lasted through a vast period of time. New Red Sandstone.-This is the newest formation of the country under notice; for wherever it is associated with other deposits it is always found to rest upon them. It fills all the lower part of the basin of the Eden, from the neighbourhood of Brough to the shores of the Solway Firth. At Maryport it is cut off by the coal measures; but it reappears at St. Bees Head, and strikes along the coast to the estuary of the Duddon and the western promontories of Low Furness; and it is seen in a few spots on the shores of Morecambe Bay. In some parts of this long coast range it seems to have been entirely washed away, and in other places it is covered by enormous heaps of diluvial drift, the colour of which is derived from the abraded fragments of red sandstone. If we cross to the other side of Morecambe Bay, we meet with the same great formation on the coast of Lancashire; and it may then be traced, through the plains of Cheshire, to the great red central plain stretching across our island from the mouth of the Tees to the mouth of the Severn. Glacial Era.-Frequent mention has been made in this work of the evidences of a past glacial era which everywhere meet the eye of the visitor who has had his attention called to the subject. In the valleys, and high up on the sides of the mountains, the rocks are observed to be smooth, rounded, and scratched. Perched blocks of stone, often of a nature differing from the rocks on which they rest, and which evidently have been carried from their parent rock over hill and dale, are to be seen on every hand. Heaps of loose stones, terminal moraines, are found in scores of places; and near the head of almost every glen are round grass-covered mounds, some of which are partly washed away by the streamlets, and exhibit a mass of boulders and loose earth. These were evidently formed when the glaciers were being melted, and are composed of the stones and earthy matter which fell upon the ice from the neighbouring mountains. The hollows in which rest many of the most picturesque tarns have evidently been formed by the last and smallest glaciers which descended the mountain precipices, scooped out the hollows, and formed embankments on the opposite side. Blocks of Eskdale granite have been transported to the plains of Lancashire and Cheshire; and also blocks of the Shap granite have been carried to the eastern coast of Yorkshire. Undoubtedly they have been borne to those places by ice, but whether on icebergs or glaciers is doubtful. Most of the English Lakes occupy ground anciently covered by immense glaciers, and those lovely sheets of water are gradually diminishing in size, being filled up by matter washed from the neighbouring plains and mountains. Derwentwater and Bassenthwaite undoubtedly formed, at one time, a lake about 10m. long, and the river Greta, and other tributaries to the Derwent River have brought down matter which has formed the level land in the Keswick Vale. In like manner have other lakes been separated, such as Buttermere and Crummock. In some places ancient lakes and tarns have existed where are now only swamp and bog. It is probable that future geologists may be able to estimate the time which has elapsed since the glacial era, by observing the average quantity of matter annually deposited in the lakes and tarns, and then measuring the quantity already accumulated. Considering the small changes which the weather has effected on the rounded and grooved rocks, and on the erratic blocks of granite found away from the district, lying bare on the surface; and the existence in every glen of round grassy mounds which often have preserved the shape they took when originally deposited, we come to the conclusion that the sea has not covered this district since the glacial era, and that that era was comparatively recent. H. I. J. BOTANY. THE variety in soil, elevation, and temperature, characterizing the Lake District, produces a corresponding variety in its Flora. In the following list will be found the more interesting and rare of the flowering plants to be met with, and also a complete catalogue of the ferns. The arrangement is according to the Natural Orders. |