68 REPORT OF TOE 



hundred feet of caps, window sills and water table were work- 

 ed out, and about two hundred feet of door sills. About one 

 hundred and twenty cords of rough stone are annually sold for 

 building purposes. 



At Crawford's quarry, on the shore of Lake Huron, about 

 eighteen miles beyond Presque Isle, this limestone presents 

 characters which create the hope of very interesting develop- 

 ments. The roek here is compact, fine-grained and handsomely 

 clouded by the unequal distribution of the bituminous matter, 

 so that polished surfaces of the general mass present quite an 

 elegant appearance. The large dome-shaped coral, however, 

 spoken of as occurring at Thunder Bay Island and Little Tra- 

 verse Bay, produces in the stone at this quarry a very beautiful 

 effect. The undulating concentric laminae, when cut by right 

 planes, and the surfaces polished, exhibit a beautiful agate-like 

 structure, the effect of which is greatly heightened by the cor- 

 alline disposition of the calcareous matter, and the varied dis- 

 tribution of the bituminous color. Should it be proved that this 

 sort of rock can be procured in samples sufficiently large, the 

 Lake Huron marble will take its place by the side of the most 

 highly esteemed varieties. 



The agricultural capabilities of the district underlain by this 

 group of rocks' is very great. The whole of the elevated lime- 

 stone region north of the line joining Thunder and Little 

 Traverse Bays, is capable of supporting a dense population. 

 The contrast noticed in passing from the arenaceous soils of the 

 Marshall and Napoleon Groups, to the calcareous soils of the 

 Helderberg Group, is very striking. The islands of Bois Blanc 

 and Mackinac, but especially the former, are covered with a 

 growth of timber, which, except the addition of a few scat- 

 tered Coniferce, is a perfect reproduction of the forests of 

 Monroe county, and Northern Ohio. The same might have 

 been said' of the plateau upon the Niagara limestone, extending 

 west from Centralia, on Drummond's Island. I saw here the 

 beech, black birch, sugar maple, and other trees growing t© 

 an enormous size. One birch measured 10 feet in circumfer- 



