52 ROZELLE PURNELL HANDY 



had been so many mole hills, and left as souvenirs of their 

 visit bowlders picked up 200 miles north. The direction of 

 transportation was determined by tracing the rocks and 

 bowlders to those parts of the continent where they were 

 derived. Masses of native copper have been found in In- 

 diana and Illinois that were transported from the Lake 

 Superior region. From the Connecticut valley bowlders 

 of red sandstone were carried to Long island, and giant masses 

 of rock have been found in the Mississippi valley 1,000 miles 

 away from their native stratum. As reasoned by Agassiz, 

 moving ice is the only known agent adequate for transpor- 

 tation on so vast a scale. The reason given for the uniform- 

 ity of the direction of moving is the immutable law that a 

 glacier moves in the direction of the slope of its upper sur- 

 face. The snows being more abundant to the north during 

 the glacial area, and the temperature being lower than at 

 the south, the accumulation naturally became greater in 

 the north; as a result, the movement would be southward. 

 South America had its corresponding glacial era, transporta- 

 tion taking place in the direction of the equator. The cold 

 of the era is attributed to the elevation and extension of 

 Arctic lands and a corresponding increase in Arctic land ice. 



In 1862 Prof. A. Ramsay aroused a great controversy 

 among geologists regarding this glacial theory. He claimed 

 a new and novel effect for glaciers, and set forth his opinion 

 in a paper read before the London Geological society. The 

 basins of the Alpine and various British lakes he attributed 

 to the erosive action of ice, while his opponents held that the 

 effect of ice is abrasive, not erosive. Although Ramsay's 

 theory won many supporters among his contemporaries, it is 

 generally rejected by the best geologists to-day. 



The logical confirmation of the glacial theory added one 

 more period to the history of the earth, which modern geology 

 has now divided into four grand epochs — archsean time, 

 paleozoic time, mesozoic time, and cenozoic time. These 

 epochs are divided into periods, with reference to the character 

 of the fossil evidence of former organic life contained in their 

 respective strata. Paleozoic time, which was probably three 

 times longer than all later time, contains three ages : the Silurian, 



