202 On the Trap Tuff of the Connecticut Valley. 



on the back side of Mount Tom. In West Springfield, another 

 narrow deposit is marked, as if imposed directly upon the princi- 

 pal range of trap ; though it is doubtful whether there may not 

 be sandstone interposed. Some very interesting boulders of one 

 variety of this rock have been found in Amherst, torn off proba- 

 bly from the back side of the trap range running northerly through 

 Sunderland, Deerfield, and Greenfield, where we still find a sim- 

 ilar rock forming a part of the range. I have, also, seen many 

 years ago, boulders of the tufaceous conglomerate, a few miles 



know not. 



any 



Organic Remains. 



The extreme paucity of organic remains in the new red sand- 

 stone of New England, and the highly igneous character of most 

 varieties of the trap tufa, would lead us scarcely to expect any ani- 

 mal or vegetable relic in the rock under consideration. But in fact 

 a single very distinct example does occur. It is a vegetable stem, 

 from one to three inches in diameter, scarcely flattened. I found 

 it in boulders of the porphyritic trap that has been described, 

 scattered m abundance over the fields, in Amherst. I have not 

 been able to trace it to its place in the mountains. But a simi- 

 lar rock abounds along the east side of the trap range running 

 through Deerfield and Greenfield, and that too in just the direc- 

 tion from which the drift of Amherst has been derived. But in 

 the ledges I have not found any vegetable stems. The largest 

 boulder m which I have found these stems, is about two feet in 

 diameter, and three of these stems run parallel to one another 

 entirely through it, and do not diminish much in size, so that 

 probably they were five times that length. The rock is a dark 

 gray trap, not at all vesicular, yet occasionally containing prehnite 

 and being porphyritic. But the stems are changed into what I 

 nave called a volcanic slag, being highly vesicular, resembling 

 the toadstone of the geologists. I think this fact may be ex- 

 plained very reasonably ; but it will be better understood when 



rocks. 



formation 



that 



unique specimens ; 



several of these 



-~~ v v "" ^d th e state collection of Massachusetts. Still 



farther I should state, that I have given a description of them 

 with a poor drawing, in my Final Report on the Geology ° 

 Massachusetts : althouo-h T wa« thom nw;^ ^ «<■<>* th^m to r^ 



x -~™7 — — *-*& 

 tions of the trap tufa. 



, 



