THE PENNSYLVANIAN PERIOD. 



555 



parallel, lay west of the 117th meridian, Carboniferous strata are known 

 at various points. They make up the body of the Blue mountains 





Fig. 249. — Section showing the relations of the Carboniferous system at one point 

 in the vicinity of Tintic, Utah. € (Tintic quartzite) = Cambrian; C (Mammoth 

 limestone) = Carboniferous ; mz (monzonite) and srh (rhyolite) = igneous rock; 

 Pal= alluvium. The section shows that much of the sedimentary rock was dis- 

 turbed and displaced by the extrusion (or intrusion) of the lava. Length of sec- 

 tion about 3 miles. (Tower, U. S. Geol. Surv.) 



in Oregon, 1 they occur in the Klamath mountains of northern Cali- 

 fornia and southern Oregon, 2 at many points in the western 

 portion of the Sierras in California, 3 and probably in the Cascade 

 Mountains of Washington. 4 It is possible that the Carboniferous seas 

 surrounded the great land area which lay between longitude 117° 

 and 121° in the vicinity of the 40th parallel, and which had an unknown 

 extension north and south. 



North of the United States, Carboniferous strata (largely Lower 

 Carboniferous) outcrop on the west side of the northward continu- 

 ation of the Great Plains, 5 and perhaps on the east. The strata of 



■ 



ig. 250. — Structure near Bisbee, Ariz. ps = pre-Cambrian ; £b and €a = Cam- 

 brian; Dm = Devonian; M e = Mississippian ; Ca = Pennsylvanian ; Qfd= Quater- 

 nary; gp = granite porphyry (Triassic or Jurassic). Length of section, a little more 

 than one mile. (Ransome, U. S. Geol. Surv.) 



these belts are probably continuous beneath the younger strata which 

 occupy the surface between them and they are probably also con- 



1 Lindgren, Science, Vol. XIII, N. Ser. 1901, p. 271. 



3 Diller, Am. Jour. Sci., Vol. XV, p. 348, 1903. 



3 Folios U. S. Geol. Surv., and King, Geol. Surv. of 40th Parallel, Vol. I. 



A - Smith, G. O. Mount Stuart, Wash., folio, U. S. Geol. Surv. 



6 Dawson, Science, March 15, 1901. 



