41 



with sand the rock ridges are generally farther away, and show a vari- 

 ation in their composition. Speaking carefully we may say that "clay 

 is a soft earth which is plastic and may be moulded with the hunds, 

 consisting of alumina, to which it owes its plasticity, and also silica 

 with water." Putting it chemically we get alumina (Oy Al^,) silica 

 (SiO,) and water (Ho O). 



It results from the slow disintegration of one of the constituents of 

 granite rocks, and when chemically pure is called alumina. The 

 farther from the source of formation the purer is the clay, the nearer to 

 its source the more sand is mixed up with it. 



Lime, magnesia, oxide of iron and other ingredients are often 

 present. The oxide of iron is a very common and abundant factor 

 along the Ottawa Valley. 



By careful examination the basins of ancient rivers can be easily 

 followed, with their rapids and stretches of calm water. Even the 

 small bays of olden times may be noted. The kinds, qualities and 

 layers of sand must be our guide, always aided, of course, by the con- 

 figuration of the immediate locality. Having referred to the qualities 

 of sand and clay we shall now specify. 



So far as soils are concerned they may be said to come from two 

 kinds of rock, granite and trap. Granites consist of quartz, feldspar and 

 mica, the latter generally an insignitlcant factor. Quartz is tiint, or the 

 silica of the chemist. When the granite hills and ridges are washed 

 down by water the coarse quartz sand lies along the sides and at the 

 immediate base of the hills, while the feldspar is ground to a fine 

 tenacious clay and is carried forward into the valleys. Henc3 the soil 

 in the flats of granite districts consists of a cold, stiff, wet and impervi- 

 ous clay which needs much manure, draining and labour to make it prc- 

 ■luctive. The hillsides are almost useless, as they consist nearly 

 altogether of quartz grit. Such are the Quebec slopes of the district 

 we are now studying, bub their valleys are too narrow, cramped and 

 water hedged to give sufficient space for the sifting out of the feldspar 

 from the quartz silt. Hence these narrow valleys are formed of 

 ground-down feldspar and the finer quartz sand, the coarser being left 

 along the mountain sides and close to their bases. lb is on this 

 account that the French habitants rejoice in their moderately fertile 



