SUMMARY. 



There are more than fifty mineral species in this region. 

 Of these, twenty are indigenous. That is, they are not due to 

 the transporting power of glaciers. They may most truly be 

 considered to represent the mineralogy of regions whose rock 

 floor is formed by the Niagara limestone. They are sulphur, 

 galena, sphalerite, millerite, pyrite, marcasite, quartz, hematite^ 

 limonite, calcite, dolomite, siderite, aragonite, kaoiinite, gyp- 

 sum, melanterite, gas, petroleum, asphalt and lignite. Of these 

 the hydrocarbons and sulphur, gypsum and melanterite arise 

 from chemical changes through which other substances have 

 passed. Whether the hydrocarbons of the region come from 

 the decomposition and destructive distillation of plants or of 

 animal remains or of both is not known. Possibly an analysis 

 of the oil for free nitrogen and sulphur might shed some light 

 upon the question, since a high percent of these elements is 

 thought to suggest an animal origin. An examination of the 

 shales which contain them, possibly the Hudson River shales, 

 might give some indication. The sulphur, gypsum and melan- 

 terite arise wholly or in part from the decomposition of that 

 very common mineral, marcasite. Marcasite is very well rep- 

 resented here, both as to its crystallography, its chemistry and 

 its mode of occurrence. Its great abundance in positions 

 where there is reason to think that its crystallization was rapid 

 lead to the conclusion that the more stable form of the iron 

 sulphide represents that crystallization which is dependent upon 

 favorable conditions. The occurrence of millerite in sphaler- 

 ite is to be noted. A general survey of the mineral composi- 

 tion of the surrounding country gives a suggestion that the 

 amount of silica in the earth's crust as commonly recorded, 

 has been overestimated. 



