Decembek 4, 1896.] 



SCIENCE. 



815 



The similar Potomac clays were formerly 

 pronounced quite destitute of animal re- 

 mains by geologists of eminence, but hard 

 work disclosed their treasures. The coast 

 east of the Hudson has an abundance of 

 the same strata, and offers still greater re- 

 wards to explorers. The Gay Head In- 

 dians are not hostile, but will be found ac- 

 tive assistants in the good work, while 

 holding fast to the traditions of their an- 

 cestors as to the volcanic origin of their 

 narrow sea- scourged home. 



LONG ISLAND SOUND. 



It is evident that we know the remnants 

 only of the great formation we are now 

 discussing, for the larger part of it has 

 long since been swept away, and much of 

 the remainder is covered up or obscured by 

 later deposits. The origin of this forma- 

 tion is a great question in itself, while its 

 gradual destruction offers still larger prob- 

 lems to the geologist. One of these only 

 I have time now to touch upon, and that 

 has special interest for me, as day by day 

 from my study window I look across the 

 Sound to Long Island. 



The origin of Long Island Bound was 

 doubtless largely dependent upon the soft 

 Jurassic clays that once filled its bed. 

 The barrier on the north was the rock- 

 bound New England coast essentially as it is 

 to-day. The outer barrier, now removed or 

 beneath the ocean, was perhaps of less du- 

 rable material, and, as the coast subsided, 

 gradually succumbed to the assaults of At- 

 lantic waves. The great terminal moraine 

 at the close of the glacial period proved a 

 second barrier, and the waters from the 

 melting ice and the larger rivers sought an 

 outlet to the sea, both east and west, and 

 thus a channel was formed in the soft clays 

 and sands that the strong ocean currents 

 gradually enlarged to its present size, 



CONCLUSION. 



The problem now before us is the presence 



or absence, on the Atlantic coast, of strata 

 of Jurassic age. The exact position where 

 such deposits should be found, if present, is 

 well known to all geologists familiar with 

 our eastern border. The fresh- water Trias- 

 sic beds below this position and the ex- 

 tensive marine Cretaceous above have long 

 been carefully studied and their exact 

 limits defined. 



For many hundred miles, along the line 

 where the Jurassic should occur, there is a 

 well-marked series of fresh-water clays and 

 sands quite distinct from anything else on 

 the coast, and the question is, — are these 

 beds of Jurassic or Cretaceous age ? The 

 prevailing opinion hitherto has been strongly 

 in favor of the latter, although this view 

 separated two allied fresh- water formations, 

 and still left out the great Jura, so well 

 represented in other parts of the world, and 

 especially in our own Eocky Mountain re- 

 gion. 



How difiicult it is to lay aside precon- 

 ceived opinions, everyone knows. The 

 long supposed absence of the Jurassic on 

 the Atlantic coast seems to have blinded 

 those who had the formation under their 

 feet. The evidence to-day in favor of its 

 presence, if not conclusive at every point, 

 is vastly greater than the opposing testi- 

 mony. Moreover, its acceptance explains 

 at once a mystery of long standing — why 

 the records of Jurassic time were not pre- 

 served here in their true place. 



To call this peculiar Atlantic formation 

 Cretaceous in its various eastern outcrops, 

 when the western expansion of the same 

 characteristic deposits has been proved Ju- 

 rassic, is certainly not scientific. To do this 

 in the light of present testimony, including 

 the animal remains, vertebrate and inverte- 

 brate, the unique structure and materials 

 of the strata themselves, and especially 

 their definite position where the Jura should 

 be, is to violate the laws of evidence. 



'So geologist familiar with the facts will 



