272 SPARKS FROM A GEOLOGIST'S HAMMER. 



Salt Group) at 916 feet; but the brine obtained at this 

 point possessed 96 of strength.* 



A subsequent year witnessed another confirmation of 

 what had been only a geological inference. I had all 

 along pointed out the existence of the Onondaga Salt 

 Group underneath the peninsula, and expressed the be- 

 lief that it must prove more productive than in central 

 New York. I advised the enterprise of boring into that 

 formation to test its productiveness; but it was onl}^ when 

 the Port Austin well became a success that the theory 

 received its verification. Rock salt was subsequently dis- 

 covered at Alpena, and at Goderich in Ontario, where it 

 has become an important article of commerce. Still later 

 experiments have developed an excellent supply of brine 

 at Manistee, and also at Muskegon. 



The geological inference of gypsum in the ridge south 

 of Tawas has been also fully confirmed. During the war, 

 a srentleman wrote to me for an indication of favorable 

 localities for speculative explorations. I directed him to 

 the ridge in question. An inexpensive boring determined 

 the existence of a heavy bed of gypsum. He took a claim, 

 as I have been informed, in exchange for an old rifle. 

 After a little excavation the gypsum was fully exposed, 

 and he sold his claim for a large sum of money.f 



* This discovery, was embodied in the articles written this year (1862) for the 

 Merchants'' Magazine and the Amer. Jour, of Science. It has been shown by later 

 artesian borings that all the formations of the peninsula are somewhat saliferou^, 

 while in the Huron Group, those substances known as " bitterns " exist in pre- 

 dominating abundance, and give origin to the celebrated *' mineral wells " of 

 Michigan. 



+ It is of course necessary to say that the speculator neglected several things. 

 He never compensated the author of his good fortune. lie never thanked him 

 for the advice. He never even reported to him the result. He did not even 

 inform the purchasers of his claim who had guided him to the discovery. Finally, 

 the present owners of the quarry, it is to be supposed, arc not oppressed with 

 anxiety over the toil and study which guided to the development of the valuable 

 property. 



