64 NEW YORK STATE MUSEUM 



well, but on them, already disturbed by earlier displacements, the 

 features chargeable to the disturbance can not always be distin- 

 guished from older ones. All three of the mountain-forming com- 

 pressions seem to have been controlled by the same relationship 

 of forces and adjustments of movement, for the results are in each 

 case the production of folds or faults of similar orientation and a 

 final structure of uniform trend. 



Deposition had been going on for ages, chiefly on the west and 

 north side of the older crystallines ; but with a return of sedimenta- 

 tion a decided reversal is noted. The Atlantic border is depressed 

 and much of the interior region seems not to have been subjected 

 to further deposition from that time even to the present. 



d Mesozoic time. Again conglomerates, sandstones and 

 shales were laid down upon an eroded floor. From their condition 

 and lithology it is believed that they are partly of continental, flood 

 plain, origin. The series is thick, generally assigned to the Triassic 

 period and is extensively developed. During the time of accumula- 

 tion and to some extent subsequent to it, there was extensive 

 igneous activity pouring out and intruding basic basaltic matter in 

 large amount. The Palisade diabase sill, and the Watchung ]\Ioun- 

 tain basalt flows are the best examples. 



At a later time small faulting occurred making frequent dis- 

 placements in this series. But mountain-folding has not again 

 visited the region. Such breaks as there are, are of the nature of 

 overlaps and disconformities rather than of the revolutionary his- 

 tory indicated by a true unconformity. One of these inter\'als 

 occurs in the ^lesozoic between the Triassic and Cretaceous. Above 

 it the thick series of Cretaceous shales, marls, sands and clays are 

 developed. Succeeding this series a similar interval represents the 

 earhest Cenozoic time. 



c Early Cenozoic time. The earliest Cenozoic (Eocene and 

 Oligocene) has no sedimentary record within this region. 



There are small remnants of deposition representing ^Miocene and 

 Pliocene time. Above these again the record is blank up to the 

 time of the glacial invasion. 



/ Late Cenozoic time — glacial period. By some combina- 

 tion of conditions not very well understood, the chief features of 

 which no doubt are. — (i) continental elevation and (2) shifting 

 of centers of precipitation and (3) modification in the composition 

 of the atmosphere, a period of excessive ice accumulation was 

 inaugurated. Ice finally covered immense continental areas and 



