436 Dana — Submarine Hudson River Channel. 



that of the Lower Cretaceous, that the clays of the Cretaceous 

 series in JSTew Jersey were laid down, and still later, when salt 

 water again reached the present New Jersey shores, so that 

 Cretaceous marine life there abounded. 



The above explanation does not account for the great depth 

 of the outer part of the channel ; and nothing but a supposi- 

 tion with a perhaps can do it. And here is one such. Perhaps 

 when the Jura-Trias beds were nearly completed, the sea-border 

 region over a wider surface continued to rise until the height 

 was sufficient to allow of excavation to a depth of 2500 feet or 

 beyond. 



This supposition has these facts in its favor : 



(1) The closing part of the Jurassic period and the whole of 

 that of the Lower Cretaceous are unrepresented on this Atlan- 

 tic border by marine rocks. 



(2) The Jura-Trias period ended in a semi-glacial era, as is 

 admitted by all who have studied the beds. The evidence con- 

 sists in thick deposits of stones and bowlders in which occur 

 masses 2 to 4 feet in diameter, and therefore such as on.y ice 

 could have handled and transported. They are situated along 

 the western side of the areas in Virginia, Maryland and New 

 Jersey (where the dip of the Jura-Trias beds is eastward) and 

 on the eastern in Connecticut and Massachusetts (where the dip 

 is westward). Fontaine has found in Virginia and Maryland 

 that they are the later beds of the formation. Prof. Edward 

 Hitchcock, in his Massachusetts Geological Report (1841), de- 

 scribes the conglomerate as largely developed at Mt. Toby, and 

 at the mouth of Miller's River on the Connecticut, north of 

 Amherst, and as containing many bowlders 3 to 4 feet in diam- 

 eter ; and he refers the conglomerate to "the upper beds" of 

 the Jura-Trias series. At the mouth of Miller's River the piles 

 of stones and bowlders brought down by the glacier of the 

 Glacier period are of like coarseness and character. 



In Connecticut similar deposits occur on the east border of 

 the Jura-Trias in East Haven, within three miles of Long 

 Island Sound, as described in this Journal by E. O. Hovey, in 

 1889 ; and they contain bowlders of granite, gneiss, trap and 

 other rocks, of various sizes up to two and a half feet in diam- 

 eter. The source of the granite and gneiss is to the southeast- 

 ward, but a mile off ; and over the two miles beyond to the 

 Sound, there are only low hills and hence no elevations for 

 making ice and glaciers. 



The hypothesis suggested above supplies the elevation and is 

 elastic enough to give them whatever height was necessary for 

 the result. 



If the time of the sea-border emergence for the formation of 

 a " submerged Hudson River channel," is taken to be that of 



