Dr. BiGSBY on the Geography and Geology of Lake Huron . 209 



III. Account of an Explosion in a Vein of Pyrites. 



This explosion took place^ sixteen years ago, in the township of Yonge, 

 near the Lake of the Thousand Isles in the St. Lawrence. At the time^ a 

 man was seeking his cow in the woods, within a short distance of the spot. 

 On a sudden he was startled by a tremendous explosion, attended by volumes 

 of smoke, and sulphurous odours. 



Three years since, on being informed of these particulars, I visited the 

 place. It is half a mile within the woods north of the road from Brookville to 

 Kingston, near to the easternmost of two creeks, about ten miles from the 

 former town. 



I found, on the summit of a quartzose mound from 30 to 40 feet high, a 

 i-ound cavity, 12 feet deep, 12 long, and 9 broad. Its sides consisted of very 

 shattered quartz spotted brown by oxide of iron, and covered profusely with 

 acicular yellow and white crystals of sulphur. The lower parts of the cavity 

 were studded with masses of iron pyrites, of which there is a vein at the bot- 

 tom of the cavity. It is a foot and a half thick, and disseminates itself into the 

 surrounding quartz. This vein may be seen, running east with a very high 

 dip, to the distance of a yard and a half. 



Similar phenomena have been noticed in a mountain in Vermont (vide Ame- 

 rican Journal of Science for Feb. 1821), and in the country towards the head 

 of the Missouri (y'lde Travels of Captains Lewis and Clarke). 



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