walco-i,.] SYNOPSIS. 365 



Sect, xr disintegration bad prepared an immense amount of material 

 for the advancing sea to assort and rearrange in early Cambrian time. 

 This, with that worn from the solid rocks by the attack upon the coast 

 line, was largely disposed of prior to the opening of the limestone- 

 forming period — an epoch varying in relative time in the various 

 provinces. 



I do not think it probable that any considerable amount of sediment 

 accumulated in the southern portion of the Interior Continental area dur- 

 ing early Cambrian time. The sections of the Charaplain Valley, eastern 

 Tennessee, Utah and Nevada, and of British Columbia prove the accu- 

 mulation of from 10,000 to 12,000 feet of sediment along the eastern and 

 western flanks of the pre-Cambriau continent before the sea deposited 

 ttie formations about the Llano Hills of Texas, the Ozark Mountains of 

 Missouri, and other portions of the Interior Continental Province. This 

 evidence leads to the belief that the continent stood at a considerable 

 elevation, and that the great accumulation of sediment during late 

 Algoukian and early Cambrian time resulted from the distribution of 

 material worn from the shore by the waves and brought into the sea by 

 the rivers of the Interior Continental region and the outlying ridges. 1 



DESCRIPTION OF PLATE II. 



Map of the central portion of the North American continent, to illustrate the rela- 

 tive thickuess of the strata composing the Cambrian group in the various geologic 

 provinces. (The small ring with the dot in the center indicates the geographic loca- 

 tion of the base of the section.) 

 The sections are grouped into the following geologic provinces: 

 Atlantic Coast Province. 

 Appalachian Province. 

 Kocky Mountain Province. 

 Interior Continental Province. 

 The latter consists of the Central Interior or Upper Mississippi, the Western or 

 Rocky Mountain, the Southwestern or Arizona and Texas, and the Eastern or Adi- 

 rondack sub-provinces. 



Atlantic Coast Province : 



Section 1. Conception Bay, Avalon Peninsula, Newfoundland. — The Cambrian rocks 

 of the Avalon Peninsula rest unconformably upon strata of Archean and Algonkian 

 age. The section represented is formed by the union of portions of those of Manuel's 

 Brook, Kelly's, Great Bell, and Little Bell Islands. 



Section 2. Vicinity of St. John, New Brunswick. — This section is unconformably 

 superjacent to the Archean, and unites the section at the city of St. John and that 

 of Hauford's Brook. 



' It is not improbable that the area of the great coastal plain of the Atlantic slope was then an ele- 

 vated portion of the continent and that much of the sediment deposited during Cambrian and later 

 Paleozoic time was washed from it into the seas immediately to the west. If this be true the source 

 Of much of the sediment of the Appalachian series of rocks is accounted for and the absence of the 

 deposits of the eastern coastline is explained by the sinking of the coastal region during, or at the 

 close of Paleozoic time. This view is strengthened by the presence, in the Middle Cambrian fauna 

 of Alabama, of a number of species that are closely allied to if not identical with species of the Mid- 

 dle Cambrian fauna of Newfoundland aud Sweden. This fauna is unknown in.the Appalachian Prov- 

 ince north of Alabama, This leads to the inference that it was distributed along the shore of the 

 Atlantic Coast Province, aud that the line of deposits, unitiug the Newfoundland and Alabama areas, 

 south of the Massachusetts area, are now buried deep beneath later deposits. 



