Regular Meeting, September 5th, 1864.
Vice-President, Dr. Eckel in the Chair.
Nine members present. Prof. B. Silliman, Jr., Dr. Eichler, and Mr. Ehrenberg as visitors.
Donations to the Cabinet: A specimen of a wild cherry from Catalina Island, by Mr. J. E. Clayton. A collection of plants from Washoe, by Mr. Bloomer.
Prof. B. Silliman remarked that in his recent visit to Arizona, east of the Mohave, he had seen what he presumed were the morains of former glaciers on the eastern flanks of some of the mountain ranges. They consist of rudely stratified materials both angular and round, mingled confusedly together and forming terrace-like spurs or embankments radiating outwards from the curved range and appearing to have been left there by glaciers, though no glacial polishing and scratching of the rocks could be seen as in the Sierra Nevada opposite Mono Lake and elsewhere. These evidences of glaciers in Arizona were nearly under the 35th parallel of latitude, and he believed that no evidence of glacial action had before been observed on the Pacific slope at a point so far south.
Prof. W. P. Blake observed that this was certainly the first observation upon glacial phenomena in Arizona, and that he had noted evidences of former glaciers in the Sierra Nevada, as far south as the Tejon Pass, lat. 35°, where there were large blocks of granite deposited for miles beyond the opening of the valley.
Prof. Silliman described the peculiar character of the outcrops of the veins in the regions of the El Dorado Cañon. He found that nearly all vestiges of the sulphurets were removed from the outcrops, while they abounded below. The outcrops gave little indication of the metal-bearing character of the veins. He had observed as he believed, at least three distinct periods of volcanic activity in that region of the Colorado and Mohave, two of which periods were sub-aqueous, and the last sub-aerial. The lava-streams generally appeared to have been poured out after the face of the country had already assumed its present form. The volcanic outflows though extensive had not materially modified the topography of the country.
Mr. Ehrenberg stated that the copper ores in the vicinity of La Paz, and Mineral City, Arizona, were generally argentiferous, sometimes giving results by assay as high as $200 per ton. The ores beyond that district did not appear to contain much. The quicksilver ore at the Eugenie vein contained both silver and copper.
Doctor Behr presented the following paper: