Chautauqua Grape Belt. 133 



like that which forms the bed rock of the region, a careful examina- 

 tion shows tliat there are many which are foreign to this part of 

 New York. Thus granites, sandstones and limestones are found in 

 a region which froin the bed rock yields only shales and sandy 

 shales. If we could examine the soil particles with a microscope, 

 we should find them to be composed of minute rock particles, fresh 

 and unchanged, as if worn or ground from tlie rock bj some strong 

 force. The entire mass is put together without arrangement, and 

 there are no distinct layers such as those found in the lower gravel 

 soils. We say it is unstratified, though sometimes (as in figure 53) 

 there is a partial stratification, never very distinct. 



This soil varies greatly in thickness, being usually several feet 

 deep; but while sometimes, particularly in the stream valleys, it 

 attains a depth of several hundred feet, in other places on the hill- 

 sides it forms a very thin veneer over the shale rock. Near the 

 crest of the escarpment there is another belt of soil of morainic 

 origin ; but as this is not in the true grape belt, it need not be con- 

 sidered here. 



This clay soil is the same as thai which covers the greater part of 

 the area of New York and New England, and of Canada to the 

 north of these districts. Its characteristics and origin are well 

 understood by geologists, to whom it is known as till or houlder 

 clay. In the first half of this century its origin was in dispute ; but 

 we now know that it is a deposit from a great continental glacier 

 which occupied northeastern North America, and extended outward 

 in all directions from a center near Hudson Bay or Labrador, 

 behaving like the present ice sheet of Greenland, or the Antarctic. 

 Slowly moving across New York State, toward the south, with a 

 depth certainly as great as a mile (for it covered the highest mountains 

 of the east), it ground down the rocks, reducing them to a fine clay, 

 which is often called rock flour, and caused a mingling of pebbles 

 from various sources. Thus the granite fiom the Canadian high- 

 lands is stranded on the hillsides of Chautauqua county and is there 

 mingled with the shale. The grooved and scratched pebbles show 

 that this process of grinding was in operation. 



Much of this material was dragged beneath the ice; and owing 

 to variations in the topography of the land, in currents or in supply. 



