AMERICAN GEOLOGT — DECADE OF 1840-1849. 389 



In a paper read before the fifth session of American Geologists and 

 Naturalists in 1844, Prof. Edward Hitchcock described a trap tufa 

 differing 1 . from "common trap" in being conglomerate and apparently 

 Hitchcock on the carrying organic remains. He believed that this was 

 Connecticut Valley produced before the main ridges of trap along the 



and on Inclination . 



of strata, 1844. Connecticut Kiver. by precursory outbursts ol pumice, 

 scoria, ashes, and melted matter falling oyer the bottom of the ocean, 

 where it became admixed with sand and gravel. After this layers of 

 sandstone accumulated over it, and finally the main ridges of trap were 

 protruded through the strata, tilting them up. 



He regarded the dip of the sandstone in the vallej" as due in part to 

 elevation by the protrusion of the trap and in part to the lifting aud 

 lateral movements of the adjoining primary ridges. He felt, however, 

 that the sandstone might have been originally deposited on a slightly 

 inclined plane. This last view brings up a matter which seems often 

 to have seriously troubled the earlier geologists, and which, so far as 

 the literature shows, was never solved for itself, but became lost sight 

 of as other and satisfactory means of accounting for the phenomenon 

 were observed. This relates to the inclined position of strata how 

 much of it was due to original deposition and how much to upheaval. 

 Cleaveland, it will be remembered, in his work on geology and 

 mineralogy. L816, expressed a doubt as to whether the inclined posi- 

 tion of strata was original or due to some powerful cause which had 

 elevated them from horizontally. Maclurein 1825 suggested that the 

 dip, so far as the transition rocks were concerned, might result from 

 their having been laid down on a primitive floor, concerning the posi- 

 tion of which nothing was known. Hitchcock, it will be noticed, with 

 his usual caution, felt that both causes might have been instrumental 

 in producing the dip observed. 



At the same session at which Hitchcock read the paper noted above, 

 Benjamin Silliman, jr., presented a report On the Intrusive Trap of 

 the New Red Sandstone of Connecticut. His conclusions were to the 

 effect that the sandstone was let down from suspension in water in 

 the inclined position which it now occupies and that it had suffered no 

 change in dip, excepting in immediate connection with the injection 

 of the trap rocks. He considered it probable that the strata were 

 deposited by a primeval ocean current setting from the southwest and 

 west. Subsequent to this accumulation and consolidation the lower 

 primary rocks were disrupted, the igneous rocks injected through the 

 fissures and distributed along the lines of least resistance in the sedi- 

 mentary strata — that is, along and up the plane of the dip, thereby 

 lifting the strata parallel to the clip from the beds on which they had 

 before reposed. At the same time there were produced in the upper 

 strata fissures and transverse cracks which were filled with the molten 

 trap. This injection he thought was probably continued during a 



