. Annual report of the Board of Regents of the Smithsonian Institution. Smithsonian Institution; Smithsonian Institution. Archives; Discoveries in science. AMERICAN GEOLOGY DECADE OF 1850—1859. 435 In the paleontological report by Dr. B. F. Shumard there were described Carboniferous fossils from Washington and Crawford coun- ties, Arkansas, and Cretaceous forms from Fort Wichita and the Cross Timbers regions of Texas. Hitchcock, in his report, dwelt particularly on the possible Carbon- iferous age of various beds of coal, reported by Shumard, and the economic value of the gypsum, as well as th
. Annual report of the Board of Regents of the Smithsonian Institution. Smithsonian Institution; Smithsonian Institution. Archives; Discoveries in science. AMERICAN GEOLOGY DECADE OF 1850—1859. 435 In the paleontological report by Dr. B. F. Shumard there were described Carboniferous fossils from Washington and Crawford coun- ties, Arkansas, and Cretaceous forms from Fort Wichita and the Cross Timbers regions of Texas. Hitchcock, in his report, dwelt particularly on the possible Carbon- iferous age of various beds of coal, reported by Shumard, and the economic value of the gypsum, as well as the ores of copper and gold. His reference to the canyons of the Red River is particularly interest- ing in view of his early writings regarding the Connecticut (p. 31<»): You seem in doubt whether this gorge was worn away by the river or is the result of some paroxysmal convulsion. You will allow me to say that I have scarcely any doubt that the stream itself has done the work. The fact that when a tributary stream enters the main river it passes through a tributary canyon seems to me to show conclusively that these gorges were produced by erosion and not by fracture. Two papers on the subjects of rock decay and erosion, of this year, are worthy of con- sideration. Prof. Oliver P. Hubbard, of Dartmouth College, during a study of the trap dikes, noted that the same could be traced continuously across the countiy, at varying levels, from mountain top to From this fact he argued that the valleys had been carved out through decomposition and erosion since the dikes were formed. The difference in altitude at the various outcrops gave, then, a measure of the amount of erosion. Dana's observations, though of a some- what different nature, were none the less interesting. In writing on denudation in the Pacific, he took the ground that the ocean is power- less to excavate valleys along the coast, and that the deep valleys like those of Tahiti are due to subaerial decomposition and
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