42 



fields. In some places the writer has noticed solid bodies of feldspathic 

 clay, but always at a distance from the rock ranges. This clay is 

 known to many nnder the appellation oi pipedaj, and is finer in tex- 

 ture and more coherent than marl. 



Trap I'ocks on the other hand, consist of felds[)ar and hornblende. 

 From this we see that f Idspar is common to both granite and trap. 

 Out of 100 parts of feldspar there are 65 parts of silica, 18 of alumina 

 and 17 of jrotash and soda ; while of 100 parts of hornblende there ai'e 

 42 parts of silica, 14 of alumina, 12 of lime, 14 of magnesia, 14 of 

 oxide of iron. A granite soil in addition to the silicious sand consists 

 chiefly of silica, alumina and potash, derived from the feldspar. A 

 trap soil, in addition to the silica, alumina and potash of the feldspar 

 contains also much lime, magnesia and iron oxide, derived from its 

 hornblende. Hence as a hornblende soil, or more comprehensively a 

 trap soil, contains more of the inorganic substances most imjjortant to 

 plant composition, it is moi'e valuable because more productive than 

 granite soil. 



There are a few fine stretches of the former, but many of the 

 latter, along the Upper Ottawa. Using this method of comparison, we 

 must conclude that the Upper Ottawa region will never be a first class 

 farming country ; at the very best it can only expect to be considered, 

 middling. 



But we must return to our line of general observation. Large 

 tracts containing thousands of acres, like the Dhalk Tlivei' Plain, are 

 difficult to explain. The student must travel to the mountains miles 

 away, and take in the difterent ranges, their bearings and the vArious 

 streams and rivers which have operated during the long ages of the 

 past. In fact it is necessaiy to make out the differences of water level 

 over vast areas and the causes of the changes in the water line. 



It is remarkable to see hovv the terraced work of Morrison's Island 

 fits into the lower system of terraces at the mouth of Black River, 

 where it enters the Culbute. These points are about ten miles apart. 

 The broad Chalk River Plain corresponds in its two levels with the 

 two definitely marked stejipes standing out on the Laurentians near the 

 head of Coulorige Lake. These two points are at least thirtv miles 

 apart. They appear to have been formed during the same water level. 



