, 332 



Peninsula, south of Saginaw Bay, have a general dip north-westerly, 

 while the dip along the southerly and westerly border of the basin of 

 coal bearing rocks, is such as to indicate the counties of Clinton and 

 Gratiot as occupying nearly the central part of the coal basin. This 

 being the case, the carboniferous sandstones, with their included coal 

 beds, may be considered as extending far to the north of the Saginaw 

 and Grand Rivers, possibly as far as to\vn twenty -three north, or to the 

 head waters of the Maskego and Tittabawassee Rivers. This supposi- 

 tion, the character of that region, as well as the dip of the rocks, would 

 seem to warrant. But the country alluded to, is, at present, in an unin- 

 habited condition ; the surface, moreover, is very generally level, and so 

 completely overspread by the deposits of diluviums and tertiary clays, 

 as totally to conceal the rock formations. Surveys have, however, been 

 extended into that region, so far as was practicable with the means af- 

 forded, and much valuable information is collected. 



If I am correct in the above conclusion, the coal bearing sandstones, 

 or, strictly speaking, the coal basin, occupy an extent of surface, ueai'ly 

 oval in form, whose centre very neai-ly corresponds with the true centre 

 of the Peninsula. The tract thus embraced is 150 miles in length, 

 north and south, and upwards of 100 in extreme breadth; covering an 

 area of about 11,000 square miles, or one-fourth the entire area of the 

 Lower Peninsula. 



It may be added, that the average dip of all the rocks described, does 

 not probably exceed 15 feet in the mile; though the dip may be said 

 to vary, at different points, from 10 to 20 feet per mile. 



BORINGS AT THE SALT WWLL, GRAND RAPIDS. 



The borings for salt at the village of Grand Rapids, Kent county, 

 commenced in the limerock stratum, mentioned above, as constituting 

 the terminating rock of the coal basin. At this point, several of the 

 next succeeding series of sandrocks appear to have thinned out, and 

 their place is hei-e occupied by alternating sti-ata of clay slates and sand- 

 stones, with gypseous marls and beds of gypsum. These continued to 

 a depth of one hundred and ninety feet, and below this the borings 

 have been carried mostly through series of sandrocks, to the depth of 

 four hundred and fifteen feet. 



Two beds of beautiful crystalized gypsum were passed through, at a 

 depth of about sixty feet, and were found to be from four to six feet in 

 thickness. This gypsum, it will be recollected, from the notice of it in 



