SURFACE OF TIIK EAliTII. 



: <>!< TIIK EARTH. 



which manifesto a decklnl dependence on eome of the greater features 

 ! phyaical geography. TIuw the abundantly spread detritus from 

 tli,- ruiiiberUnd mountains croon the inland to Tynemouth, one 

 reaches the cout of Yorkshire, but does not cross the Pennine chnin 

 of iiu'iintains, except at one point (Stainmoor), though it spreads alonj 

 the western aide of it as far south as Manchester and the plains 01 

 Cheshire and Staffordshire. In like manner the detritus from the 

 Western Alps has been carried on to the Jura, and lies in a strange 

 manner in nil parts of the hollow of the Lake of Geneva, and on UK 

 iimihUxl SnK-ve Mountains; yet it has been observed that the lines 

 fallowed by the boulders are those of the great valleys, so that each 

 great valley has been the direction in which were carried the blocks 

 ir.'in the head of that valley. 



5. It is observed that often the largest blocks contained in a mtaa ol 

 tliis detritus lie at the top, resting on the smaller gravel and sand ; and 

 ili it lvl..\v the whole mass the hard rocks are scratched by parallel 

 ilMinet small grooves or stria, marks of the dragging movement to 

 which the stones were subject in their passage. 



6. Though in some coses successive deposition con be traced in the 

 parts of such a mass, it is very often seen that the materials are 

 entirely unarranged, mere heaps of stones, and sand or mud ; the 

 stones being often indiscriminately stuck in clay, large and small, heavy 

 and light, absolutely without any stratification, such as long suspension 

 in water must certainly have produced. 



7. Finally, amidst such confused masses, bones of land quadrupeds, 

 mostly or entirely of extinct species, and even of extinct genera, occur, 

 and locally even in abundance. These are, however, more common 

 in laminated lacustrine deposits resting upon the diluvial masses, or 

 perha)>s covered by them. 



With the mammalian remains alluded to are not unfrequently 

 associated, as has recently (1S61) been shown, flint implements of 

 human work ; indicating, if not proving, the contemporaneity of some 

 of the now and long since extinct mammals with certain races of man. 

 (IVcstwich, in ' Phil. Trans.,' 1860.) 



It was thought possible to explain these characteristic phenomena 

 by many local inundations, or one general and overwhelming flood, 

 capable of overcoming many of the lesser inequalities of surface-level, 

 but modified in its course by the larger ranges of mountains and 

 valleys. And as in the northern zones of the world (which have been 

 much investigated in this respect) there is a very frequently observed 

 ilireetien of the boulders to the south or south-east, it has been pro- 

 posed for consideration whether some great change of the level of land 

 and sea in the circumpolar regions might account for what seems a 

 general fact. But further, as the most abundant deposits of this 

 nature have been drifted from particular chains of mountains, as the 

 Cumbrian group in Englaud, the primary mountains of Norway, the 

 Alps, &c , all which districts have undergone elevation at some time, it has 

 been thought that their upward movement may have been the cause of 

 the displacement and transport of the blocks. (Buckhnd, ' Reliquiae 

 Diluvianic ; ' Elie de Beaumont, ' Sur les Revolutions du Globe,') 



It has, however, been proposed to account for the distribution of 

 the boulders by a more gradual action of the waters of the sea. If 

 the region of Cumbrian rocks, for example, and a very large portion 

 of the north of England, were supposed to be raised from the sea, by 

 a continual or intermitting movement, so as to bring successively 

 under the action of the breakers the whole country to the east and 

 south-east of the area now occupied by the Cumberland mountains, 

 this would allow of a continual drifting of the boulders to the east and 

 south, by the continual tendency of the tides and currents of the sea. 

 (Phillips, in 'Treatise on Geology, &c. ;' Whewell in Murchison's 

 ' Silurian System.') Floating ice has been represented as adequate to 

 carry off from the shore where it was formed masses of mud and 

 fragments of rocks, and, by melting or turning over, to spread them 

 on the bed of the sea. This sea-bed raised would show the accumu- 

 lations from such icebergs, often in narrow bands or insulated patches, 

 such a really occur, and have been long celebrated, among the heaps 

 of Norwegian detritus which lie on the sandy plains of North 

 Germany. (Lyell, ' Principles of Geology,' ' Manual of Elementary 

 Geology;' Murchison, ' Silurian System.') 



Finally, ice in another form has been appealed to for the explanation 

 of these phenomena. The formation of glaciers 'in mountain valleys 

 is such as to permit of their forward movement down a slope, and their 

 carrying with them in their progress fragments of rocks and heaps of 

 gravel and mud which by any cause foil upon their surface. These 

 heaps of " moraine " accumulate along the sides and at the lower termi- 

 nation of the glacier, and the arrangement, or rather confused 

 aggregation, of the materials in them resembles very much that of the 

 mumrn to be accounted for. The surface of the rocks below a glacier 

 is scratched, as we have before stated to happen in places where 

 boulders are noticed; and as in the Alps it is certain that glaciers 

 have formerly been extended much farther from the mountain- 

 Hummits than now they ore [Sxow, PKRENXIAL], it has been con- 

 jectured that anciently, in the times coincident with or preceding 

 the boulder or drift jwriod, they were very much more extended, so as 

 even to have reached from the Alps to the Jura, from the mountains 

 nl Norway to those of Bohemia, and from Sbap Fells in Westmoreland 

 to the mouth of the Humber. Upon the subsequent contraction of 

 these glaciers, the moraines they had left would experience some 



changes by the action of water (melted ice), which might then run in 

 lines impossible for watery currents after the ice was fully removed. 

 (Agassiz, ' Etudes sur lea Glaciers.') On the grooves and stria; on the 

 surfaces of rocks Mr. Jukes remarks ('Popular Physical Geology,' 

 p. 280), in considering the former action of ice, here alluded to, " In 

 addition to ice however, Mr. Mallet has acutely pointed out that many 

 of these appearances may be due to what he somewhat inappropriately 

 terms 'mud glaciers,' by which he means the sliding forward or 

 slipping of great masses of clay, mud, or sand, charged with pebbles 

 and boulders, along the inland surfaces of rock, either as tin- land rose 

 from the sea, or when they were subsequently loosened by the action 

 of rain and other water." 



The examination of the boulders of certain parts of the Himalayan 

 range, and the application of the theory of glacier movement to explain 

 their distribution, has led Dr. Joseph D. Hooker to suggest some 

 modifications of that theory in respect of those localities. The banks 

 of the Great Rungeet river, near its junction with the Kulhait, consist 

 of mica-slate, cumbered, in adeep gorge through which the river Hows, 

 with enormous boulders of that rock, of clay-slate, and of granite, some 

 fully 10 feet in diameter. But the latter rock is not common at eleva- 

 tions below 10,000 feet, whereas the absolute elevation of the river 

 here is only 1840 feet; it is not easy therefore to account for their 

 present position. " They have been transported," Dr. Hooker infers, 

 " from a considerable distance in the interior of the lofty valley to the 

 north, and have descended not less than 8000 feet, and travelled fully 

 fifteen miles in a straight line, or perhaps forty along the river bed. 

 It may be supposed that moraines have transported them to 8000 feet 

 (the lowest limit of apparent moraines), and the power of river water 

 carried them further; if so, the rivers must have been of much greater 

 volume formerly than they are now." Another explanation was re- 

 quired by the enormous fractured boulders of gneiss frequent over the 

 whole of the mountain Mons Lepcha, in the Sikkim Himalaya, at 

 elevations of from 7000 to 11,000 feet. Contrary to those mentioned 

 above, they were of the same material as the rock in situ, and as unac- 

 countable in their, origin, by received theory, as the loose blocks on the 

 Dorjiling and Sinchul spurs to the south, at similar altitudes, often 

 cresting narrow ridges. Dr. Hooker measured one angular detached 

 block, 40 feet high, resting on a steep narrow shoulder of the spur, in 

 a position to which it was impossible it could have rolled ; " and it is 

 equally difficult to suppose," he observes, " that glacial [glacier] ice. 

 deposited it 4000 feet above the bottom of the gorge, except we con- 

 clude the valley to have been filled with ice to that depth." A third 

 modification of or addition to the glacier theory of boulder distribu- 

 tion, is pointed to by the locality of the Jongri spur of the great 

 mountain Kinchinjunga [OliOLOOT], over which are scattered blocks 

 of gneiss, many 20 feet in diameter. " It is not possible to account 

 for the transport and deposit of these boulders by glaciers of the ordi- 

 nary form, namely, by a stream of ice following the course of a valley ; 

 and we are forced to speculate \ipon the possibility of ice having capped 

 the whole spur, and moved downwards, transporting blocks from thu 

 prominences on various parts of the t spur." 'Himalayan Journals,' 

 vol. i., pp. 242, 253, 288. 



The entire subject of the transport of erratic blocks, and of the 

 hypotheses which have been framed to account for it, has been criti- 

 cally examined by Mr. W. Hopkins, in a paper ' On the Elevation and 

 Denudation of the District of the Lakes of Cumberland and Westmore- 

 land,' in the ' Quart. Journ. of the Geol. Soc.,' vol. iv. 



The great mass of diluvium from the Cumbrian mountains, already 

 alluded to, which covers the surface of Lancashire, rests on nothing 

 more recent than the new red sandstone, and Mr. Hopkins conceives 

 that its transport might have begun with the elevatory movements 

 which disturbed that formation, when the surface of the present moun- 

 tainous district began to rise permanently above the surface of the 

 ocean, and the valleys began to be formed. The spreading out of 

 diluvial matter that term being now adopted in its broad physical 

 sense may be regarded as the necessary consequence of wide general 

 currents, and that this has been the agency by which the mass of 

 diluvium in question has been transported to its present locality and 

 position, does not admit, in Mr. Hopkins's opinion, of the smallest 

 doubt. He accounts for the existence of currents diverging from the 

 centre of the district by a repetition of paroxysmal elevations of from 

 100 to 200 feet ; and, affirming the entire adequacy of this cause to 

 transport all the erratic blocks derived from that region, concludes 

 that such has been the agency by which that transport has actually 

 been effected. He rejects the iceberg theory in its application to the 

 case investigated, but conceives that floating ice may probably have 

 been the most efficient agent in transporting the larger blocks of colder 

 regions from their original localities. Mr. Hopkins's paper in 

 studied with great advantage with reference to the whole subject of 

 the distribution of boulders and of the northern drift. 



We do not propose to investigate any of the hypotheses above 

 stated, preceding the facts and reasoning we have derived from Dr. 

 Hooker and Mr. Hopkins. Geologists have been remarkable for 

 eagerly adopting and as easily abandoning most of them ; and others 

 might have been added merely as beacons to be avoided. It may be 

 iroper however to point out three things which may be useful to 

 remember in further prosecuting this subject, and which, indeed, have 

 neither been forgotten nor neglected, by the geologist last named. 



