50 TALCHEER COAL FIELD. 



their much rounded condition seems quite opposed to the idea of trans- 

 port by true glaciers. 



Indeed we have here no evidence whatever of the action of glaciers, 

 No dgu of action of *^® '^^P^^^'^ differing greatly from the glacial drift 

 glaciers. ^^^ Permian breccias of England. 



It must also be borne in mind that the temperature necessary to 

 allow of glaciers reaching the sea or a lake is very much lower than that 

 at which groimd ice might be formed and carried down by rivers. While 

 the existence of the former is determined by the mean temperature of 

 the whole year, the latter depends on the lowest temperature of the 

 winter season, and therefore may readily, and does, occur in countries,* 

 whose mean temperature is comparatively high, f W. T. B.J 



Immediately over the boulder bed is commonly found what we have 

 Tesselated sandstone, named the " tesselated sandstone." 

 This is a fine-grained, compact, quartzose sandstone, of a pale yellow 

 color, characteristic of this part of the series, having well-marked 

 stratification, never ferruginous, and rarely, if ever, congiomeritic. 

 The name given to it, " tesselated sandstone," is indicative of the 

 tendency which it exhibits, especially when most finely-grained to 

 weather in a very peculiar and characteristic manner, splitting up into 

 polygonal fragments of from 2 to 3 inches in diameter, and presenting 



* Thus, in the Northern part of the Black Sea, at the present day, Coast Ice is always 

 formed in winter, and this too in salt water ; the winter temperature there being equivalent 

 to that of Central Norway, which is only a degree or two South of countries in which 

 glaciers come down to the sea level ; while, on the other hand, the summer tem- 

 perature ia that of Spain. An example perhaps more to the purpose is found in Thibet, 

 ■where all the conditions, under which such a deposit as ■ that we are considering 

 might be prodaced, exist. The winter temperature of Thibet is as low as that of the 

 Black Sea, the country lying between the January Isothermals of 23° and 41'' Fahrenheit, 

 while in summer the temperature is equal to that of Sierra Leone, Ceylon and Southern India, 

 the July Isothermals being between 77° and 81° Fahrenheit. Tllis country lies only 10° to 

 IS'NorthofCuttack. 



