312 MINERALS AND GEOLOGY 



of marine or estuary species of mollusca now living in the St. 

 Lawrence Gulf. At Green's Creek, and at spots on the Madawaska, 

 200 feet above the present sea-level, some of these later deposits 

 contain also calcareous nodules inclosing well-preserved examples of 

 the capelin (Mallotus villosus), lumpsucker (Cyclopterus lumpus) 

 and other small fishes of existing species, with occasional impres- 

 sions of modern leaves, as those of the populus balsamnifera, etc. 

 To still more recent formations belong the deposits of shell-marl 

 and peat, indicating the sites of ancient ponds and swamps, which 

 overlie the surface rocks of the district in Cumberland, Plantagenet, 

 Clarence, Gloucester and other townships. Several of these peat 

 deposits are of wide extent. 



In addition to good building-stones, the more important economic 

 products comprise : The white sandstone of the Potsdam formation 

 of Nepean, available as a glass material ; the dolomitic limestone 

 of the Chazy formation of the same township, which furnishes 

 the celebrated " Hull Cement;" the "shell limestone," also belonging 

 to the Chazy strata, which is largely dressed at L'Orignal for 

 manteltops, tombstones, etc.; and the great peat beds referred to 

 above.* 



LAKE ONTARIO DISTRICT. 



This district, separated from the palaeozoic district of the Lower 

 Ottawa by the intervening gneissoid belt which crosses the St. 

 Lawrence between Brockville and Kingston and extends south- 

 wards into the wild region of the Adirondacks, is underlaid 

 essentially by Lower Silurian formations in nearly horizontal beds. 

 Viewed generally, the strata present a dip of about half-a-degree, or 

 less, towards the south-west; and, thus, in proceeding westward 

 from Kingston to Hamilton we pass from older to newer formations, 

 as shewn (but with necessarily exaggerated dip, as in all ordinary 

 sections) in the annexed diagram. The latter, however, extending 

 still further westward, shews the outcropping strata of the Erie and 

 Huron district, as well. 



The southern limit of the present district forms the entire Can- 

 adian shore of lake Ontario. Its eastern and northern limits are 



* Dr Robert Bell, of the Geological Survey of Canada, has recently expressed the opinion 

 (Ottawa*Evening Journal, Febuary4th, 1888) that a supply of "natural gas" would probably 

 be obtained by boring at suitable sites around Ottawa City. 



