Stria and Furrows of the Rocks of Western Neio York. 149 



expansion at the freezing point of water. The result of the 

 crystalline arrangement of the particles then takes place. As the 

 cold increases the ice contracts, like other bodies in the same con- 

 dition. Hence it is that ice cracks on our rivers, ponds and lakes, 

 as the cold becomes intense or is continued, and those cracks are 

 from half an inch wide to a foot, and even four feet wide on 

 the deep lakes. Hence the cracking of frozen ground when not 

 covered with snow, with such tremendous explosions. Hence 

 too the closing up of those cracks and rents as soon as the tem- 

 perature rises near the point of congelation of water. The ap- 

 plication of this principle is obvious. As the water trickles into 

 the fissures in the ice of a glacier it must be frozen, and thus 

 expanded ; as the new ice cools more, contraction takes place, 

 and new fissures or cracks must be the result. This process 

 must be continually repeated in the warmer parts of the year, if 

 the temperature of the ice below is depressed towards zero of 

 Fahrenheit. Thus the heat of the atmosphere provides the trick- 

 ling water, and congelation produces the motion by the expan- 

 sion, and the cracks or fissures are renewed by the subsequent 

 contraction. The expansion of the ice in different directions as 

 it met with less obstacles would give stria? and grooves of various 

 bearings. It is not certain the glaciers ever existed in this sec- 

 tion of the country ; it is certain that there was a rush of waters 

 from the north. 



The glacial hypothesis will not account for the position of the 

 bowlders in many places. From the Alps a glacier may have 

 transported the granite bowlders to a lower situation upon Mount 

 Jura. But in our country we often find intervening hills higher 

 than the source of the bowlders. The region south of Lake 

 Ontario, which is covered with the sandstone bowlders from the 

 shore of that lake, or a little south of the shore, is higher than 

 the position of the sandstone. In Berkshire County, Mass., bowl- 

 ders of graywacke, evidently removed from the hills of that rock 

 in the adjoining part of the state of New York, are scattered 

 through the valley of the Housatonic. But between the hills of 

 graywacke and that valley, lies the Taconic range of mountains, 

 along the boundary between the two states, and the latter are 

 every where several hundred feet higher than the former. If 

 the bowlders were once lodged on a glacier, the ice and bowl- 

 ders must have been transported by a flood of waters over the 



