16 



Relations of Geology to Agriculture 



of 60 or 80 feet. Its effects on the surface of the district there- 

 fore are chiefly to improve the soils of the limestone at the points 

 of junction, and to form occasional narrow stripes and patches of 

 stiff clay, richly calcareous, and productive in wheat. When the 

 escarpment of the Helderberg limestone is less bold than where 

 I visited it, near Syracuse, its surface is generally overspread 

 with the debris of the softer rocks which adjoin it on either side. 

 It is so in the line of the cross section N S (Section, No. III.), 

 and there the soils which cover it form a prolongation of the rich 

 land, fertile in wheat, which covers the plains below. 



In the accompanying outline map it will be seen that the belt 

 formed by these rocks (5 and 6) is very narrow in Western New 

 York. Farther to the west however it expands, and along the 

 north shore of Lake Erie it forms a wide and valuable tract of land 

 in the fast filling-up and fertile region of Western Canada. 



No. 7, the Hamilton Group, consists of olive and dark -blue shale, 

 which, when alone, forms stiff dark-coloured clays far less rich 

 in calcareous matter than the Onondaga soils. They are there- 

 fore less open and friable, and in consequence more difficult and 

 expensive to work. Still they are capable of producing excellent 

 wheat under favourable circumstances, or when properly prepared. 

 The celebrated Genessee valley rests on this formation, but the 

 natural soil of the Hamilton shales is there modified, or altogether 

 covered by drifted fragments of the Niagara limestone and other 

 more northern formations, which have been washed up the valley. 

 Hence the quality of the Genessee soils is not that which is 

 natural to those of the Hamilton group. 



This group is of great thickness, and, as is shown in the map, 

 forms a belt of land 10 or 12 miles in breadth. Where the 

 shales are rich in lime they are submitted to arable culture. 

 They are everywhere however difficult to keep clean, and are 

 especially infested with corn gromwell (Lithospermum arvense), 

 called here pigeon-weed. They are for the most part, there- 

 fore, like our own stiff clays of the lias and other formations, 

 left to perpetual grass, which they produce of excellent quality. 

 Here, therefore, the grazing and dairy country of Western New 

 York commences. 



Nos. 8 and 9. The Genessee Slate (No. 8), which is separately 

 distinguished in the cross section (No. III.), is too thin to form an 

 important agricultural feature of the country. It crumbles more 

 slowly than the Hamilton shales ; but where its fragments mix 

 with those of the Tully and other thin limestones and calcareous 

 shales beneath it — also represented in the section — it forms good 

 soils. 



The Portage and Chemung Groups (No. 9) consist of alterna- 

 tions of shales, poor in lime below, with flagstones and massive 

 sandstones. They are of enormous thickness, and extend south- 



