GEOLOGICAL KEPORT. lil 



sistsof very fine sand or elav, and Is mostly an areno-argillaceous impalpable materi 

 of light buff-color. Near Camp Floyd, in' Cedar Valley, where I had an opportum 

 to examine more closely, the upper stratum and soil is' a finely arenaceous loam: t 

 subsoil verv rough, and still more sandv, and exceedingly hard when dry. They ma 

 excellent "adobes" or sundried brick, the usual building material of the GOunti 

 Lower down it changes into nearly pure, very fine sand, with only a few particles 

 clay. This, when dry, docs not appear sandv* but forms compact pieces which readi 

 absorb water and thereby become plastic, thouirli only slightly coherent: a little mo 

 water causes it to dissolve into single grains of sand! In such beds, from a depth 

 40 feet, we Obtained a number of minute fresh-water and land shells belonging to t 

 genera Sphertum (O/r/^.v), Li/nwca, Helix, Am nimftt, tie. Near Camp Floyd, so-cab 

 saleratus-clav is found (saleratus is an expression frequently used in' that regi< 

 instead of salt, the latter name being reserved for the common salt, the chloride 

 sodium), a bluish-gray arenaceous elav, in which salts form white ervstallizatior 

 films and nodules, mostly consisting of' sulphate of magnesia, and a little sulphate 



ofmao-ucsiatoalum. (See below.) Similar clays are widely distributed. Alsocoars 

 sand occurs, in some places like a regular beach*; in others, again, as drift-sand or dee 



It would be superfluous to enumerate all the single observations which confir 

 the theorv of the prevailing lacustrine formation of the basin. That the country a 

 joining Salt Lake and Carson Lake has once been covered with water must strike evei 



plains are but little elevated above the present level of the lake, and have, beyoi 



question, 



An ele\ 



present level of the lake would flood this entire flat to a great distance, thus forming 

 a vast inland sea." If a rise of the water of a few feet would have such an effect, what 

 would not be the effect of an increase of several hundred feet to the highest water- 

 marks? 



We can entertain no doubt that such was the condition of the country at the be- 

 ginning of the present era, after the last great geological changes had taken place. The 

 position of the latest Tertiary strata, capping the highest summits of the adjoining 

 Wahsatch Mountains, proves that great revolutions have taken place at the close of 

 that period, while the deposits of the basin exhibit not the slightest signs of a disturb- 

 ance, and occupy exactly such places as thev would take, and present such features 

 as they would assume, if those agencies were renewed which led to their formation; 

 in other words, if the country was again covered with water. 



of the southwestern portion of the territory of the United States, numerous evidences 

 of which have been adduced bv all explorers. Some have tried to explain the sub- 

 sidence of the water by volcanic eruptions and consequent changes of the level; but 

 this explanation, although it may apply to single cases, is by no means satisfactory, 

 Volcanic eruptions would only throw the water to some other point, and not effect a 

 decrease of its quantity; and even if one basin was thus drained, numerous others 

 40 bu 



