BULLETIN OF THE GEOLOGICAL SOCIETY OF AMERICA 

 Vol. 27, pp. 175-192 March 31, 1916 



DEY LAND IN GEOLOGY 1 



PRESIDENTIAL ADDRESS BY ARTHUR P. COLEMAN 



(Bead before the Society December 29, 1915) 



CONTENTS 



Page 

 Introduction 175 



Discovery of the land 177 



Arid zones of the Pleistocene and present 180 



Arid period of the Permian and Triassic 181 



Late Precambrian deserts 182 



Glacial periods 183 



Pleistocene ice age 183 



Permocarbonif erous ice age 184 



Late Precambrian ice age 186 



Huronian ice age 186 



Pre-Huronian land conditions ■ 18S 



Why should there be dry land? 189 



Have oceans and continents ever changed places? 190 



Teleological considerations 192 



Introduction 



After visits to South Africa, Australia, and India to study dry-land 

 deposits, it has become very evident to the writer that most of the earth 

 is covered with water, and also that a ship is the most tantalizing of all 

 modes of travel for a geologist, since captains have a prejudice against 

 anything of geological interest, such as rocks or reefs or shoals. After 

 1,200 miles of sheltered voyaging behind the great Australian barrier, 

 one may reach Java without ever seeing a coral reef at close quarters. 

 Except the oozes dredged from the deep sea and the contours of its bot- 

 tom revealed by soundings, the three-quarters of the globe beneath the 

 ocean have scarcely any message for the geologist. That the waves and 

 the tides do important geological work is true, but to hear the growl of 

 the breakers and to see them pounce on their prey, one must travel in a 

 small boat close to shore and not in an ocean liner. Even to study the 

 action of the sea 011 the shore it is better to be on land. The dry shores 



1 Manuscript received by the Secretary of the Society January 27, 1916. 



XIII — Bull. Geol. Soc. Am., Vol. 27, 1915 (175) 



