204 



GEOLOGY OF OHIO. 



with stalactites, and the floor covered with stalagmites, many of which 

 still remain. These, as is well known, are formed by the dripping from 

 the roof of water holding lime in solution, and the precipitation of this 

 lime both on roof and floor. This precipitation could, of course, only 

 take place in air, and would be impossible in a gallery filled with water. 

 But during the last summer the interesting discovery has been made by 

 Capt. John Brown (who resides on the island, and has given much atten- 

 tion to its geology) that the floor of the cave was studded with stalag- 

 mites far below the present level of the Lake. This shows very palpably 

 (what is, however, taught by the very existence of the cave) that the lake 

 level was once much lower than at present, and that all that part of the 

 cave which is now under water was once filled with air, through which 

 the water dripped from roof to floor, precipitating its lime, as is now 

 done in the upper portions of the cav# 



The limestone of which Put-in-Bay and the adjacent islands are form- 

 ed, as proved by our numerous analyses, is nearly a typical dolomite — 

 that is, it contains more than 40 per cent, of magnesia. This composi- 

 tion of the stone has been cited as proof that it was unfit for the manu- 

 facture of lime ; but, as a matter of fact, the lime which is most esteemed 

 in the scaithern part of Ohio, and in many other portions of the country, 

 has nearly the same composition as that obtained from the Put-in-Bay 

 Island stone. For example, the lime most esteemed in Cincinnati, de- 

 rived from the Niagara group, and obtained at Springfield, Yellow 

 Springs, and Cedarville, has almost the composition of the Put-in-Bay 

 waterlime, as will be seen by the table of analysis given below. The 

 lime preferred above all others in the city of New York is that manufac- 

 tured from the Sing Sing marble, which is a typical dolomite, contain- 

 ing— 



Carbonate of lime 53.24 



Carbonate of magnesia 45.89 



Silica and alumina 87 



100.00 

 Analyses op the Massive Beds of the Waterlime Group, Put-in-Bay Island, 



MADE BY PhOF. E. W. BOOT. 



