379 



fossils are the tracks of birds. One fact in particular he had 

 noticed, that the strike of the sandstone is more to the east than 

 is generally supposed, as much upon an average as 45°. 



As to the elevation of the strata, he first supposed it to have 

 been caused by the intrusion of the trap rock. But he had con- 

 vinced himself that this is not the case, and that it has been 

 raised in some other way ; perhaps by the great crowding move- 

 ment described by Prof. Rogers, as having taken place amongst 

 the Alleghanies. The present could not have been the original 

 inclination of the strata, for it is now 40^, and the idea that birds 

 could walk on ground at this angle, leaving no traces of slipping, 

 nor even of walking on an inclined surface, is absurd. At the 

 east end there is an appearance of the strata being crowded by 

 pressure ; but there is no inversion, and no repetition of folds on 

 the whole section. 



Another inference made, was, that so great a thickness of rock 

 cannot all belong to the Trias. For, making all reasonable 

 allowance for the original deposition of the strata on an inclined 

 surface, there is still a thickness of ten thousand feet ; at least, 

 enough for the Trias, the Permian and Carboniferous, per- 

 haps, even the Devonian also. The rock on the section lying 

 below the trap ranges, is decidedly of a different character from 

 that above, and abounds in fucoids, but no other fossil has been 

 found in it. Doubtless these strata will be found to embrace 

 several distinct formations, and here is an interesting field of re- 

 search for our geologists. Other sections, however, should be 

 taken across the valley, before the inferences above made can be 

 regarded as entirely certain. But it is the opinion of President 

 Hitchcock, that the sandstone will be found quite as thick in 

 other parts of the Connecticut valley, as at Turner's Falls, 

 though, in general, not so highly inclined. 



Prof. Henry B. Rogers thought that the inclination of the strata 

 in question, might be owing both to deposition at angle, and to 

 the movement, by crowding. Where actual measurements of 

 the thickness of strata can be made, he thinks this is the only 

 safe method. In the red sandstone of the Middle States, the 

 thickness can be measured in several places ; there are instances 



