Classification of Rocks. 1& 



ing or flap:ging streets. It yields materials for glass making, and also makes 

 a good lining for iron furnaces. The species of fossils it contains are few in 

 number, but some of them of great scientific interest. In the ancient seas, 

 the materials of which this rock is composed doubtless existed in the form of 

 loose sand drifted about the bottom, and constituting extensive beaches and 

 shallows where sported numerous animals, distantly allied to the crabs and 

 lobsters of the present day, but of a generic form no longer seen. There 

 were a few small shell fish, and it appears a good deal of sea weed in this 

 ocean, as their remains are often found more or less perfectly preserved in 

 the rock. 



The Potsdam Sandstone should be found at intervals along the base of 

 the hills on the north shores of the St. Lawrence and Ottawa, from below 

 Quebec, to a point opposite Pembroke. From this latter place it forms an 

 irregular and interrupted belt southwardly through the counties of Renfrew, 

 Lanark, Leeds and Grenville, to the St. Lawrence above Brockville. It 

 also crosses from the Ottawa, near the village of St. Anns, to Beauharnois 

 and thence into the United States. West of the Thousand Islands this rock 

 should be found in a belt extending from the vicinity of Kingston westwardly 

 in the rear of the counties on the north shore of Lake Ontario, to the south- 

 east corner of the Georgian Bay. It also occurs at the Sault St. Mary. 



Calcifeeous Sandrociv. 



The Calciferous Sandrock consists of limestone, containing more or less 

 sand — some of the beds are of a shaly character, having the appearance of 

 a drab coloured greenish or yellowish hardened mud, full of petrified sea 

 weeds. The rock called by the farmers in some parts of the country, " Bas- 

 tard Limestone," belongs to this formation. In the reports of the Geoloo-ical 

 Survey of New York, it is thus described by Mr. Vanuxem, one of the Geo- 

 logists who w^as employed on that important work, " it embraces genei-ally 

 three distinct masses as to character and position — the first is silicious and 

 compact, and may probably be the continuation of the Potsdam Sandstone, 

 either in part or almost wholly," 



" The second is a variable mixture of fine yellew silicious sand and car- 

 bonate of lime, which, v/hen fractured, presents a fine sparkling grain ; it is 

 in layers, but they rarely shew that very regular structure which usually 

 belongs to a limestone rock. They have a shattered appearance from numer- 

 ous cracks, the parts being more or less separated from each other." 



'' The third is a mixture of the Calciferous material, which is usually 

 yelloAvish, very granular and sparkling when fresh broken, and of compact 

 limestone, which resembles the Birdseyc limestone in its mineral character, 

 containing also some argillaceous or slaty matter." ■'-^ 



The Calciferous Sandrock often contains cavities, lined with beautiful 

 quartz, crystals, and sometimes small rounded masses of transparent calca- 

 reous spar. It has only a few species of fossils, but contains great quanti- 

 ties of Fucoides, or petrified sea weeds. These are sometimes packed in 



* Report upon the Third District, page 30, 



