1894.] -"^1 [Lyman. 



distance in other directions from tlie outcrops of the solid undisturbed 

 trap. The surprising thing, indeed, is perhaps tliat tlie trap hills are not 

 more prominent in the midst of such soft rocks, and that the trap bowl- 

 ders and gradually decomposing rubbish should not have accumulated to 

 a still greater extent. The explanation, no doubt, is that the trap, with 

 all its hardness and, in human experience, durability, is yet in geological 

 ages comparatively easy of decomposition. At some places it is obviously 

 decomposed almost to incoherence in large masses yet in place, only made 

 visible by railroad cuts. It has therefore seemed advisable to mark the 

 trap as solid, in place, only where it appears to have occasioned hills of 

 some prominence ; and, even so, the true extent may have been exagger- 

 ated, particularly, perhaps, in the case of the Palisade trap along the 

 Hudson river, where there may well be concealed important beds of 

 shales between separate sheets of trap. 



Tt will be seen from the map that not all of the trap is in overflow 

 sheets ; but that, although none of it appears to be in intrusive sheets, 

 there are some dikes cutting across the sedimentary bedding. Surely that 

 is not to be Avondered at ; and it is not surprising that such cases of dikes 

 should occur more numerously among the older sedimentary beds. For 

 those parts of the field are the ones where the upper beds have been 

 wholly carried away by erosion, and with them whatever overflow sheets 

 may have been supplied by the still remaining dikes. 



The map shows that in New Jersey, the same as in Eastern Pennsyl- 

 vania, the structure of the New Red is much less simple near its north- 

 west border than towards its southeast ; and that the old idea of nothing 

 but northwesterly dips is far from correct. 



It is noticeable that the thickness of the New Red is much less towards 

 the northeastern end of the field than it is near the Delaware and espe- 

 cially less than in Montgomery county. Pa. ; and that the diminution is 

 occasioned by the absence of the upper beds, while the lower ones do not 

 seem to varj^ very greatly in amount. 



The diminution extends into Connecticut in greater degree, and still 

 more so in Massachusetts, as is to be seen in the accompanying map of 

 the New Red there. It is possible that the idea of the very limited pale- 

 ontological range and thickness of the whole American New Red maj'' 

 have largely originated in the small extent of the Massachusetts and Con- 

 necticut series, the earliest to be studied. Another error may perhaps be 

 traced in great part to the same source. The New Red, namel3% is per- 

 sistentlj^ called New Red sandstone ; though in Eastern Pennsylvania 

 a very small part of the beds, perhaps hardly one-twentieth, are sandstone, 

 and the rest are all shales, or at most sandy shales. In Massachusetts, 

 however, a much larger share of the diminished series would appear to be 

 sandstone ; and that fact, together with the time-honored name of the 

 English New Red sandstone was doubtless the cause of giving what is 

 lithologically so inappropriate a name to our American rocks. 



The accompanying little map of the Connecticut and Massachusetts 



