732 HISTORICAL GEOLOGY. 



in eastern North America. There was another to the eastward, the Aca- 

 dian. Range, extending from Newfoundland probably to Narraganset Bay in 

 Rhode Island, — a distance exceeding 800 miles, and still another, that of the 

 Ouachita Range in Arkansas (pages 380, 389) . 



In the Acadian trough the beds of Cape Breton and Nova Scotia are 

 variously flexed, and at the southern end of the trough, in Rhode Island and 

 part of Massachusetts adjoining, there are like evidences of disturbance ; and, 

 moreover, the coal is changed to anthracite, and in some places to graphite. 



Since the close of the Lower Silurian was an epoch of upturning for the beds then in the 

 northern part of the Acadian trough, it is probable that it was so for the whole trough, 

 including the coast of Maine and the Cambrian beds of the Boston basin. But there is no 

 direct evidence as to this or to later times of disturbance along the belt except in the Nova 

 Scotia, New Brunswick, and Maine regions. Slates, grits, conglomerates, and eruptive rocks 

 occur in the Boston basin above the Cambrian, without fossils or any other evidence of 

 age ; and, as described by Crosby and Bouve, they may be of any period from Cambrian 

 to Carboniferous. 



The three ranges, the Appalachian, Acadian, and Ouachita, constitute 

 together the Appalachian Mountain System. The length of the whole region 

 of orogenic disturbance is over 2000 miles. 



The Gaspe- Worcester trough, which contains some carbonaceous beds, 

 with graphite, at Worcester, underwent post-Carboniferous upturnings. But 

 details are wanting. 



It is probable that various dislocations and anticlines over the states north along the 

 Mississippi valley date from this epoch ; and in Illinois, several lines of dislocation, between 

 northwest and west-northwest in trend, have been described by Worthen (Geol. Bep., i., 

 1866). (1) One crosses the Mississippi in Alexander County at the " Grand Chain," where 

 the Trenton forms a ledge across the river ; (2) another at Salt Creek Point in Monroe 

 County ; (3) another below St. Louis, near the south line of St. Clair County ; (4) another 

 at " Cap au Gres," in Calhoun County, " where there is a downthrow of the beds on the 

 south side of at least a thousand feet," and the St. Peters sandstone constitutes the "Cap 

 au Gres " ; (5) another, north -north west in trend, farther north, intersecting Kock Kiver, 

 Grand Detour, and the Illinois River in La Salle County, between La Salle and Utica, 

 bringing the Lower Magnesian limestone to the surface ; (6) another, traceable from 

 Bailey's Landing on the west side of the Mississippi to Shawneetown on the Ohio. Of the 

 fifth, he states that " it elevates the Coal-measures 300' to 400', showing that the disturb- 

 ance took place at a period subsequent to the deposition of the Coal formation" ; and 

 afterward adds, with reference to the whole series of upturnings, "It is impossible, with 

 the evidence before us at this time, to fix with certainty the relative dates of these dis- 

 turbances ; but it seems quite probable that none of them date back to a period anterior 

 to the Carboniferous epoch ; for we find, in general, no want of conformity between the 

 uplifted strata and any of the superincumbent Paleozoic beds." 



There are other lines of uplift or undulations farther north across Iowa, as described 

 by McGee (11th U. S. Geol. Stirv., Annual Beport, 338, 1891), which have a trend of 

 N. 30°-40° W. The time of origin is stated to be doubtful, except for one anticline, that 

 of the Cedar Valley, near Davenport, Iowa, which ' ' does not appear to affect the Coal- 

 measures at Davenport and Rock Island." 



So far as yet ascertained no great mountain-making events occurred at 

 this time over the Summit Region of the Rocky Mountains. The Carbonif- 



