12 PROCEEDINGS OF THE INDIANAPOLIS MEETING. 



Probably no single section includes the whole, but there can be little risk of over- 

 estimate in setting the depression at 10,000 feet. Of this a great part has been again 

 elevated so as to stand above sea-level. 



In the same manner a large area in the western states of America, at present very 

 imperfectly known, consists of Mesozoic strata many thousand feet in thickness, in- 

 dicating depression to an equal amount ; but these same beds have since then been 

 elevated, and some of them now form the summits of peaks rising 14,000 feet above 

 the sea (Dana). 



Looking now across the gap that separates Paleozoic from Mesozoic time, without 

 stopping to inquire into its great significance in connection with the subject, we find 

 a striking illustration in the well-known depression in what is now the eastern states. 

 The facts are familiar. Suffice it to say that in that region a subsidence set in early 

 in the Paleozoic era and continued nearly or quite to its end, carrying down the old 

 surface to a depth in some places of not less than 40,000 feet, or 8 miles. So far as it 

 is possible to measure this area, its length was at least 2,500 miles and its breadth not 

 less than 300, and in some places two or three times as great. Yet a great part of this 

 has been filled and much of it reelevated to the height of hundreds of feet above the 

 sea. 



Similar testimony comes from the Paleozoic rocks on the other side of the Atlantic. 

 The sections there are of even greater thickness, and indicate immense depression and 

 subsequent recovery as clearly and as extensively as do those of the western world. 



Looking back to a yet earlier date, the Vindhya range in India supplies a remark- 

 able example. There an enormous mass of pre-Silurian rocks lying on disturbed 

 earlier ones indicates a subsidence of not. less than 14,000 feet, and subsequent filling 

 and elevation without alteration or disturbance. All this occurred in pre-Silurian 

 times, and the vast unfossiliferous series of the Vindhyan has existed in the same state 

 ever since (save for the effects of erosion), a monument to a subsidence equal to the 

 depth of the Atlantic basin which has been filled and lifted into a now ancient conti- 

 nental area. 



(6) A second argument urged on behalf of the opinion here under consideration is 

 that no deposits are known among the strata resembling those now forming at the 

 bottom of the deep seas. Up to a certain extent there is some force in this statement. 

 It may be true that nothing exactlj^ like the singular deposits revealed by the recent 

 deep-sea exploration has been met with in the crust of the earth. These consist 

 chiefly of two kinds of material — the ooze, mostly calcareous, of the less depths up to 

 2,500 fathoms and, below that limit, a fine red clay with nodules of manganese. The 

 former is composed of minute foraminiferous shells and the latter of volcanic and 

 cosmic matter. Regarding the former, it may be said that there is no valid objection 

 to ascribing the chalk to a similar origin. Such material indicates distance from land 

 rather than deep water at the time of its deposition, and the ooze of the Atlantic 

 ranges from 2,500 up to 500 fathoms, and even here it could not be formed unless the 

 surface layer, where the rhizopods live, were favorable to their development. 



Regarding the latter — the real deposit of the deep sea — we may remark, in the 

 first place, that it is by no means certain that we cannot match these abyssal deposits 

 among the strata. Without urging the case of the chalk, there are other materials 

 which very closely parallel some of them. Professor Nicholson says in his recent 

 " Manual of Paleontology " (p. 75) : 



" It cannot be safely asserted that we have no ancient representatives even of the ' abyssal 

 clays ' of the oceans of the present day. On the contrary, it seems very possible that certain of 



