AMERICAN GEOLOGY MAOLUREAN ERA, 1785-1819. 247 



some of those Secondary rocks in the immediate vicinity of the moun- 

 tains was noted, but some difficulty found in accounting for the same. 

 "Subsequent to the deposition of these horizontally stratified rocks," 

 he wrote, ""their position has been somewhat changed, either by the 

 action of some force beneath the primitive rocks, forcing them up to 

 a greater elevation than they formerly possessed, or by the sinking 

 down of the Secondary, produced by the operation of some cause 

 equally unknown.' 1 This matter he again referred to, thinking it pos- 

 sible, though scarcely probable, that the great and abrupt change in 

 the inclination of the strata in the parts near the granite might be due 

 to the gradual wearing away by the agency of rivers of some portion 

 of the sandstone, and that those rocks now found in an inclined position 

 were detached portions of what was formerly the upper part of the 

 strata which, having been undermined on their eastern side and sup- 

 ported by the granite on the western side, had fallen into their present 

 position. 



The presence of coal beds in the region of the Ozark Mountains was 

 noted, and the associated limestones were set down as of Carbonifer- 

 ous age, as was also the limestone of the region of the lead mines. 



An important suggestion was made relative to the possibility of 



obtaining water through bore holes sunk in the arid tract lying west 



of the Ozark Mountains. "It is not improbable," he wrote, "that 



the strata of many parts of this secondary formation 



James's Suggestion . . " , 



as to Artesian toward its exterior circumference may vary from a 



Wells. . . * 



horizontal to an inclined position, in consequence of 

 which the water that falls in dew and rains in the hill}* districts, be- 

 coming insinuated between curved stratifications, may descend toward 

 the center of the formation under such circumstances as would insure 

 its rising to the surface through well or bore holes sunk sufficiently 

 to penetrate the veins." 



The rocks of the Allegheny Mountains were classified as granular 

 limestone, metalliferous limestones, transition, argillite, and sandstone. 

 The report was accompanied by a volume of plates, which included 

 geological sections on the thirty-fifth and forty -first parallels (tig. 11). 

 These were intended to form continuations of Maclure's third and 

 fifth sections, already noted (p. 228). 



The second volume of Silliman's American Journal of Science, issued 



this year, had a long article by the editor — Sketches of a Tour in the 



Counties of New Haven and Litchfield, Conn., with notices of the 



Geology, Mineralogy, and Scenery — in which are de- 



Qeological Notes bv .i i i i 1 i_i 



siiiiman, Olmsted, scribed the various rocks passed over, among others 

 the ''primitive white marble" near New Milford. 

 He described this as "a perfectly distinct bed in gneiss, which is found 

 on both sides of it, and, of course, both above and below it." a sensible 

 admixture of the two rocks being perceptible for some feet on both 

 sides of the junction. 



