PALEOZOIC TIME — CARBONIC. 



639 



Worthen found it to consist principally of gray limestone, partly oolitic, partly eherty, with 

 some shaly beds, in all about 900'. The larger portion of the series yields Chester fossils ; 

 but characteristic forms of the St. Louis group mark the age of the lowest 250' to 300'. 



In Nova Scotia and New Brunswick, the Subcarboniferous rocks are : (1) the Horton 

 series, consisting of red sandstones, conglomerates, red and green marlytes ; and, above 

 these, (2) the Windsor series, consisting of thick beds of limestone, full of fossils, with 

 some red marlytes, and beds of gypsum, affording the gypsum exported from Nova Scotia 

 and New Brunswick. Thus the upper part is calcareous, as in Ohio, Tennessee, and West 

 Virginia. The estimated thickness is 6000'. To the north, toward the Archaean, the 

 limestones fail ; and, instead, the rocks are to a greater extent a coarse conglomerate. To 

 the south, limestones prevail. The best exposures of the lower or Horton series are at 

 Horton Bluff, Hillsborough, and other places in southern New Brunswick. 



In the lower part of these Subcarboniferous beds, as in those of Virginia, there are, on 

 a small scale, "/aise " Coal-measures, and, in one instance, a bed of erect trees, under- 

 cla^'s, and thin coal seams ; and the same beds contain numerous remains of fishes. The 

 fish-bearing shales of Albert ^line, New Brunswick, are of this period (Dawson). 



Rocky-Mountain and Pacific-border regions. — Over large portions of these regions, 

 the limestones of the Subcarboniferous have not been distinguished from those of the 

 following period. In most cases their recognition only waits for the more careful study of 

 the fossils ; but, at many points, these appear to be wanting. They have been identified' 

 in the Elk Mountains, and other ranges of the crest chain of the mountains in western 

 Colorado ; on the eastern slopes of the Wind River Mountains, in Wyoming. In Montana, 

 at " Old Baldy," near Virginia City, tjiere are fossils of the Chester group, and probably 

 the Lower Subcarboniferous beds are also present (Meek). In Idaho, near Fort Hall, 

 Bradley found masses of limestone filled with minute shells, many species of which Meek 

 has identified with forms characteristic of the oolitic beds of the St. Louis group, at Spergen 

 Hill, Ind. 



LIFE. 



Pla>-ts. — The vegetation of the period included species of Lycopods 

 of the genera Lepidodendron, Sigillaria, Knorria ; Ferns of the Devonian 

 genera, Archceopteris, Neuropteris, 



991. 



991 a. 



Sphenopteris, Od.ontopteris, with spe- 

 cies also of the new genera Aletliop- 

 teris, Lesley a ; Equiseta of the genera 

 Calamites, Sphenophyllum, and Aste- 

 rophyllites ; and Cj'cads, under Gym- 

 nosperms, of the genus Cordaites; 

 and among the fossil fruits, those 

 (f Cordaites, and probably some of 

 Conifers of the Yew family. 



AxiMALS. 1. Spongiozoans. — 



Several sponges have been described 

 of the genera Palceacis (which has 

 deep cup-like cavities), Physospon- 

 gia, etc. Hexactinellid sponges are 

 common in the beds at Crawfords- 



ville, Ind. The chert, which occurs in many beds, abounds in sponge spi- 

 cules. 



Polyp-coral. — Fig. 991, iioi-tion of the Coral, Litho- 

 strotion Canadense ; 991 a, vertical view of the same. 

 Meek and Worthen. 



