Handbook of Paleontology 223 



there is a total thickness of approximately 10,000 feet, 

 about half sandstones and shales and half limestones. The 

 Cambrian series in this Appalachian trough often be- 

 gins with conglomerates and sandstones of continental 

 origin and the finer shale material is encountered as 

 one goes westward. Other sections show mainly 

 limestone upon the basal sandstone, but such deposits 

 could be formed only in those portions of the trough 

 bej^ond the reach of sediments washed from the lands. 

 The Lower and Middle Cambrian deposits on the At- 

 lantic side of Appalachia (the Atlantic province) occur 

 in eastern Massachusetts, New Brunswick, Cape Bre- 

 ton and eastern Newfoundland. These beds are sev- 

 eral thousand feet thick in Cape Breton. There is a 

 progressive overlap toward the oldland and the beds 

 thin out, being wholly wanting or replaced by conti- 

 nental deposits at St John, New Brunswick, where the 

 marine Cambrian deposits begin with the Middle Cam- 

 brian. The best representative of the Lower Cam- 

 brian, as well as of the Cambrian as a whole, is found 

 in the region of the Cordilleran trough, the deposits of 

 which were derived from the Cascadian land mass to 

 the west. One of the thickest sections measured, of 

 about 6000 feet, was found in the Cordilleran trough 

 near Waucoba Springs in Inyo county, California, 

 hence the Lower Cambrian in the west has been called 

 the Waucobian series. These deposits are largely 

 sands, often Proterozoic residuals worked over by the 

 advancing sea. There is a continuous overlap of beds 

 eastward, and they are much thinner in Nevada and 

 the Great Basin region. In the Appalachian trough 

 the marine waters were largely withdrawn toward the 

 close of the Lower Cambrian, and the sea did not claim 



