172 proceedings: geological society 



terrestrial factors affecting climate and the varying relations of the 

 ocean and the air under differing conditions of temperature as well as 

 reactions involved in exposure of fresh areas to oxidation and weather- 

 ing. The ingenious hypothesis of the cause of glaciation advanced by 

 Chamberlin as a result of these studies is full of suggestive ideas which 

 but few students have as yet had time adequately to consider. 



As to the manner in which the ice sheet accumulated on the North 

 American continent very little has as yet been determined. Conditions 

 are much more complex here than in Europe and a solution seems likely 

 to require about as elaborate an investigation as is required to determine 

 the cause of the ice age. If, as seems likely, the Labrador center was fed 

 by moist air currents from the Gulf of Mexico, and the Keewatin by 

 those from the Pacific, it becomes a problem to* explain the recently 

 announced Patrician center north of Lake Superior. It is also difficult 

 to account for the development and great extent of the Keewatin center 

 under present conditions of altitude and slope. There are, however, 

 indications that in early Pleistocene time the coast ranges of Alaska 

 were much lower than now and they may have had less influence in 

 checking the winds from the Pacific and in causing precipitation to be 

 chiefly near the coast. 



There is wide difference of opinion concerning the climatic conditions 

 at the time of loess deposition and it remains to be determined whether 

 the loess is interglacial or glacial. The opinion is almost unanimous 

 that it is chiefly of eolian deposition, water being influential merely in 

 distributing it down the great waterways and exposing it to the action 

 of the \vind. To what extent the loess is derived from the glacial ma- 

 terials and to what extent from the semi-arid western plains is unde- 

 termined. 



The question of a stage of glaciation closely connected with the main 

 loess deposition is still open. It is here that the lowan glacial stage 

 was originally placed. Opinions on the lowan drift are-now quite di- 

 verse, its existence being questioned by some, its Illinoian age being 

 claimed by others, while a number of geologists still place it close to the 

 main loess deposition and claim for it a much later time that the Illinoian. 



The 279th meeting was held at the Cosmos Club, February 11, 1914. 



Under the head of "Informal Communications," Dean Winchester 

 described the anticlines of eastern Montana, Wyoming and North 

 Dakota. 



Regular Program 



The Camwnball marine member of the Lance formation: E. R. Lloyd. 

 The Lance formation in parts of the Dakotas consists of two parts; 

 a lower part, approximately 400 feet thick, with predominant somber 

 colored shale and yellow sandstone, of continental origin; and an upper 

 part, about 300 feet thick of sandstone, shale, and limestone of marine 

 origin. To this upper part the name Cannonball marine member is 

 given. The lower sediments of continental origin contain a flora which 



