222 New York State Museum 



with those of northern Scotland. From New Jersey and 

 Pennsylvania south to Alabama the deposits of the Appa- 

 lachian trough have been profoundly disturbed. On the 

 Atlantic side of Appalachia the Cambrian deposits have 

 an Atlantic fauna and the series shows a clear correspon- 

 dence with that of Sweden which also belongs to the 

 Atlantic province. Remnants of these deposits occur 

 in eastern Massachusetts, New Brunswick, Cape Bre- 

 ton and Newfoundland. Cambrian rocks are also 

 found in the interior bordering the older crystallines 

 where they appear at the surface. Although patches 

 of outcropping Cambrian rocks are of wide extent in 

 North America many deep wells that have penetrated 

 to the Precambrian floor show that their extent un- 

 der cover of younger strata is much more limited than 

 was formerly believed. 



In eastern North America the Lower Cambrian is 

 restricted to the Appalachian geosyncline and these 

 rocks have been called the Taconian series because they 

 were first studied and recognized as a system in the 

 Taconic mountains of eastern New York by Prof. 

 Ebenezer Emmons of the New York State Survey. 

 This series was previously termed Georgian from 

 Georgia, Vermont, where Lower Cambrian beds occur. 

 The Lower Cambrian sediments of the Appalachian 

 trough show great thicknesses in places. They are 

 thickest in the south suggesting that the trough was 

 invaded from the south and transgression took place 

 northward with accompanying overlap of successive 

 horizons. In Vermont and northeastern New York 

 there are about 3000 feet, 1500 feet consisting mainly 

 of slates and quartzites and 1200 feet of marble and dolo- 

 mite. Through Pennsylvania, Maryland, and Virginia 



