Page:Walcott Cambrian Geology and Paleontology II.djvu/35

 6. The apparently abrupt appearance of the Lower Cambrian fauna is therefore to be explained by the absence on our present land areas of the sediments, and hence the faunas of the Lipalian period. This resulted from the continental area being above sea level during the development of the unknown ancestry of the Cambrian fauna.

I fully realize that the conclusions above outlined are based primarily on the absence of a marine fauna in Algonkian rocks, but until such is discovered I know of no more probable explanation of the abrupt appearance of the Cambrian fauna than that I have presented.