268 ANNUAL OF SCIENTIFIC DISCOVERY. 



soluble substances as were originally embraced in the marine deposits 

 from which the rocks were formed. Were there any point in the 

 margin of one of these rocky basins lower than its central portions, 

 chance for escape of all its soluble contents would have existed ; and 

 it is doubtful whether in such case brines could have been retained 

 to the present day, in any considerable quantity. Our subterranean 

 peninsula basins are comparable with the superficial basins in which 

 the salt lakes of the world are located. Neither class of basins has 

 an outlet. The basin of Lake Superior was once filled with water as 

 salt as that of the Great Salt Lake. Both have received accessions 

 of fresh water but while one has been drained by an efflux which 

 has continually carried away some portions of the chloride of sodium, 

 the other has been drained only by evaporation. The salinencss of 

 one has been reduced almost to an infinitesimal quantity ; that of the 

 other is unimpaired, if it has not actually been strengthened by the 

 loss of more water than it has received." 



The subterranean salt-basins of Michigan are three in number, and, 

 unless all geological indications are fallacious, they contain the most 

 abundant and accessible salt deposits upon the North American con- 

 tinent, east of the Mississippi. The principal basin extends from 

 Grand Rapids, in Kent County, to Sanilac County, and to an un- 

 known distance toward the north. "Within this distance," says the 

 State Geologist, "the area covered by the coal measures maybe taken 

 as the area underlain by the saliferous strata of maximum productive- 

 ness." These strata are made up of a remarkable series of salt-bear- 

 ing shales, with intercalated beds of gypsum and limestone, and with a 

 maximum thickness, according to the authority above quoted, of 184 

 feet. The principal salt wells of Michigan are now located in the Sagi- 

 naw Valley, and their present annual product is upwards of 2,000,000 

 bushels per annum ; a growth in two years equal to that attained to 

 by the Onondaga Saltworks of New York in 1834, thirty-eight years 

 after the salt springs had passed under the superintendence of the 

 State. Such, rnoreoA r er, is the strength and abundance of the brine 

 furnished by the Saginaw wells, and the cheapness of fuel, that a 

 barrel of salt can be made for sixty-four cents ; while the cost of the 

 same at Syracuse, New York, is at least ninety-five cents. 



The annual consumption of salt in the United States for the year 

 1S59 was estimated at fifty-two and one-half pounds per capita, or 

 in the aggregate about 30,092,000 bushels. Of this amount not 

 quite fifty per cent, is of domestic manufacture, the balance being 

 an imported article. In 1858 the amount of salt received in the city 

 of Chicago was 333,988 barrels, a fact which at once indicates the 

 importance of the salt trade of the United States at the West. 



GEOLOGICAL SUMMARY. 



Sulphur from Sicily. The exportation of sulphur from Sicily, 

 during 18CO, amounted in the aggregate to 1,794,593 cwts., of which 

 648,141 cwts. went to England, 525,976 to France, 96,462 to Hol- 

 land and Belgium, 154,436 to Naples, 3.620 to the rest of Italy, 

 58,385 to Greece, 196,694 to America, 110,879 unknown destination. 



