Handbook of Paleontology 207 



tario, makes it more than likely that the Grenville series 

 underlies the Paleozoic of western New York likewise 

 (figure 22). In that case, during Grenville time a great 

 expanse of ocean must have covered most, if not all of the 

 state. The character of the sediments indicates deposition 

 in a shallow transgressing sea and that the waters were 

 warm. As the limestones disappear and give way to 

 quartzites, gneisses and schists (original sands and mud) 

 toward the Hudson Bay region, the indications are that the 

 source of the material was in this region and that this 

 part of the Canadian Shield must then have already 

 existed as a continental area. After the deposition of the 

 Grenville sediments there occurred a period of igneous 

 activity on a large scale when great masses of molten rock 

 were pushed into the sediments from below, breaking up 

 the Grenville into patches. These rising batholiths domed 

 up the strata above so that, due to the extensive erosion 

 that followed the uplift of the great mass of Grenville 

 sediments and associated rocks into the first known Adi- 

 rondack Mountains, the sedimentary rocks are now found 

 only in the deeper Grenville synclines between which are 

 the igneous domes. Minor igneous activity toward the 

 close of the Precambrian resulted in the formation of 

 dikes which cut across these deep-seated igneous rocks, 

 showing their younger age. 



The crystalline limestones are the most striking forma- 

 tions of the Grenville series in the Adirondacks. They 

 are more often colored and contain graphite, mica, horn- 

 blende and serpentine, but sometimes there is a coarse 

 white marble. Serpentine is common in these marbles 

 and the fossillike Eozoon canadense. The crystalline 

 limestones are found most abundantly on the north- 

 western side of the Adirondacks where they occur in 



