386 



NA TURE 



\_Augtist 26, 1880 



The next great European chain in point of age is that of the 

 Ural, which^according to Mnrchison is of pre-Permian age, a 

 fact proved by the Permi.in conglomerates which were formed 

 from the waste of the older strata. On these they lie quite 

 uuconformably and nearly undisturbed on the western flank of 

 the moimtain=. 



In North America the great chain of the Alleghany Mountains 

 underwent several disturbances, the last (a great one) having 

 taken place after the deposition of the Carboniferous rocks, and 

 before that of the New Red Sandstone. The vast mountainous 

 region included under the name; of the Rocky Mountains, after 

 several successive disturbances of upheaval, did not attain its 

 present development till after the Miocene or Middle Tertiary 

 epoch. 



In South America, notwithstanding many oscillations of level 

 recorded by Darwin, the main great di>tm-bance of the strata 

 that form the chain of the Andes took place apparently in post- 

 i-yctaccotis times. 



The Alps, the rudiments of which began in more ancient 

 times, received their greatest disturbance and upheaval in po^t- 

 I'^ocene days, and were again raised at least 5,000 feet (I believe 

 much more) at the close of the Miocene epoch. The Apennines 

 the Pyrenees the Carpathians, and the great mountam region on 

 the east of the Adriatic and southward into Greece, are of the 

 same general age, and this is also the case in regard to the Atlas 

 in North Africa, and the Caucasus on the borders of Europe and 

 Asia. In the north of India the history of the Great Himalayan 

 range closely coincides with that of the Alps, for while the most 

 jiowerful known disturbance and elevation of the range took 

 jilace after the close of the Eocene ep^ch, a subsequent elevation 

 occurred in post-Miocene times closely resembling and at Iea»t 

 equal to that sustained by the Alps at the same period. 



It would probably not be difficult by help of extra research t" 

 add other cxses to this notice of recurrences of the upheaval and 

 origin of special mountain chains, some of which I have spcken 

 of from personal knowledge ; but enough has been given to sho>v 

 the bearing of this question on the argument I have in view, 

 namely, that of repetition of the same kind of events throughout 

 all known geological time. 



Salt and Salt Lakes. — I now come to the discussion of the 

 circumstances that produced numerous recurrences of the deve- 

 lopment of beds of various salts {chiefly common rock-salt) in 

 many formations, which it will be seen are to a great extent 

 connected with continental or inland conditions. In compara- 

 tively rainless countries salt; are often deposited on the surface 

 of the ground by the effect of solar evaporation of moisture from 

 the soil. Wa'er dissolves certain salts in combination with the 

 ingredients of the underlying rocks and soils, and brings it to the 

 surface, and when solar evaporation ensues the salt or salts are 

 deposited on the ground. This is well known to be the case in 

 and near the region of the Great .Salt Lake in North America, 

 and in South America in some of the nearly rainless districts of 

 the Cordillera, extensive surface-deposits of s.alts of various 

 kinds are common. The surface of the ground around the Dead 

 ■Sea is also in extra dry seasons covered wilh salt, the result of 

 evaporation, and in the upper provinces of India (mentioned by 

 Medlicott and Blanford) "many tracts of land in the Indo- 

 Gangetic alluvial plain are rendered worthless for cultivation by 

 an efflorescence of salt known in the North-West Provinces as 

 J\eli" while every geigrapher knows that iii Central Asia, from 

 the western shore of the Caspian Sea to the Kinshan Mountains 

 of Mongolia, with rare exceptions nearly every la! e is salt in an 

 area at least 3,500 miles in length. This circumstance is due to 

 the fact that all so-called fresh-water springs, and therefore all 

 rivers, contain small quantities of salts in solution only appre- 

 ciable to the chemist, and by the constant evaporation of pure 

 water from the lakes, in the conrseof time, it necessarily happens 

 that these salts get concentrated in the water by the effect of 

 solar heat, and, if not already begun, precipitation of solid salts 

 must ensue. 



The earliest deposits of rock-silt that I know about have been 

 described by Mr. A. ]J. Wynne of the Geological Survey of 

 India, in his memoir "On the Geology of the Sail Range in the 

 Punjab."' The beds of salt are of 'ureat thickness, and along 

 with gypsum and dolomitic layers occur in marl of a red colour 

 like our Keuper Marl. '1 his color.r I have for many years con- 

 sidered to be, in certain cases, apt to indicate deposition of 

 sediments in inland lakes, salt or frtsh, as the case may be, and 



V '. ^I''"5f.f^''''"' n°''"s and descriptions of the Salt Range might be quoteJ, 

 but Mr. Wynne's is enough for my purpose. 



with respect to these strata in the Punjab Salt Range, authors 

 seem to be in doubt whether they were formed in inland lakes 

 or in lagoons near the seaboard, which at intervals were liable 

 to be flooded by the s;a, and in which in the hot seasons salts 

 were deposited by evaporation caused by solar heat. For my 

 argument, it matters but little which of these was the true 

 l^hysical condition of the land of the time, though I incline to 

 think the inland lake theory most probable. The age of the 

 strata associated with this salt is not yet certainly ascertained. 

 In " The Geology of India" Medlicott and Blanford incline to 

 consider them of Lower Silurian age, and Mr. Wynne, in his 

 " Geology of the Salt Range," places the salt and g)'psum beds 

 doubtfully on the same geological horizon. 



The next salt-bearing formation that I shall notice is the 

 Salina or Onondaga Salt Group of North America, which forms 

 part of the Upper Silurian rocks, and lies immediately above 

 the Niagara Limestone. It is rich in gypsum and in salt-brine, 

 often of a very concentrated character, "which can only be 

 derived from original depositions of salt," and it is also supposed 

 by Dr. T. Sterry Hunt to contain solid rock-salt 115 feet in 

 thickness at the depth of 2,085 f^^'i "^^"^ Saginaw Bay in 

 Michigan. 



In the Lower Devonian strata of Russia near Lake Ilmen, Sir 

 R. Murchison describes salt springs at Starai Russa. Sinkings, 

 " made in the hope of penetrating to the soin'ce of these salt 

 springs," reached a depth of 600 feet without the discovery of 

 rock salt, " and we are left in doubt whether the real source of 

 the salt is in the lowest beds of the Devonian rocks or even in 

 the Silurian system." 



In the United States brine springs also occur in Ohio, Penn- 

 sylvania, and Virginia, in Devonian rocks. 



In Michigan salts are found from the Carboniferous down to 

 the Devonian series ; and in other parts of the United States, 

 Western Pennsylvania, Virginia, Ohio, Illinois, and Kentucky, 

 from the lower Coal-measures salts are derived wdiich must have 

 been deposited in inland areas, since even in the depths of inland 

 seas that communicate w-ith the great ocean, such as the Medi- 

 terranean and the Red Sea, no great beds of salt can be depo- 

 sited. Before such strata of salt can be formed, supersaturation 

 must have taken place. 



In the North of England, at and near Middlesborough, two 

 deep bore-holes were made some years ago in the hope of reach- 

 ing the Coal-measures of the Durham coal-field. One of them 

 at Salthome was sunk to a depth of 1,355 f^^'- ^"'5' '''^y 

 passed through 74 feet of superficial clay and gravel, next 

 through about 1,175 f^^' °f ''^'i sandstones and marls, with beds 

 of rock-salt and gypsum. The whole of these strata (excepting 

 the clay and gravel) evidently belong to the Keuper marls and 

 sandstones of the upper part of our New Red series. Beneath 

 these they passed through 67 feet of dolomitic limestone, which 

 in this neighbourhood forms the upper part of the Permian 

 series, and beneath the limestone the strata consist of 27 feet of 

 gypsum and rock-salt and marls, one of the beds of rock-salt 

 having a thickness of 14 feet. This bed of Permian salt is of 

 some importance, since I have been convinced for long that the 

 British Permian strata were deposited, not in the sea, but in salt 

 likes comparable in some respects to the great salt lake of Utah, 

 and in its restricted fauna to the far greater salt lake of the 

 Caspian Sea. The gypsum, the dolomite or magne.-ian lime- 

 stone, the red marls covered with rain-pittings, the sun-cracks, 

 and the impressions of footprints of reptiles made in the soft 

 sandy marls w^hen the water was temporarily lowered by the 

 solar evaporation of successive summers, all point to the fact 

 that our Permian strata were not deposited in the sea, but in a 

 salt lake or lakes once for a time connected with the sea. The 

 same may be said of other Permian areas in the central parts of 

 the Continent of Europe, such as Stassfurt and Anhalt, Halle 

 and Altern in Thuringia, and Sperenberg, near Berlin, and also 

 in India.' 



Neither do I think that the Permian strata of Russia, as 

 described by Sir Roderick Murchison, were necessarily, as he 

 implies, deposited in a wide ocean. According to his view all 

 marine life universally declined to a minimum after the close of 

 the Carboniferous period, that declire beginning with the Per- 

 mian and ending with the Tn issic epoch. Those who believe 

 in the doctrine of evolution will find it hard to accept the idea 

 which this implies, namely, that all the prolific forms of the 

 Jurassic series sprang from the scanty faunas of the Permian 

 ■ See " Physical Geology and Geography of Great Britain," 5th edition, 

 where the questiuo is treated in more detail. 



