PREFACE 



Dr. Antevs' study of the recession of the last ice sheet from 

 New England is something new and significant. It differs so 

 much, indeed, in method from previous studies by glacialists in 

 America, and the range of its applications is so wide, that no 

 brief introduction can quite do it justice. Fortunately, these 

 methods are so simple that they are readily understood and put 

 to practice. As for the broad application of such work as this 

 to solving problems of glacial history and climate and the accom- 

 panying migrations of plants and animals and of primitive man, 

 an attentive reader may form his own judgment. 



Ever since Louis Agassiz conceived the idea of former con- 

 tinental ice sheets over northern Europe and North America, 

 geologists of the two continents have been gathering evidences 

 of them. New England, the home of Agassiz almost from the 

 time when his glacial theory was announced until his death, 

 presents varied and plentiful proof of glaciation. The grooves 

 and striae on the rocks, the southward dispersion of stones and 

 boulders, and the varieties of "drift" deposits had already been 

 observed and speculated upon by Edward Hitchcock, W. W. 

 Mather, C. T. Jackson, and other pioneers in New England and 

 New York when Louis Agassiz advanced his theory of an ice 

 sheet. Although they recognized the fact that the puzzling 

 "drift phenomena" corresponded to records made by living 

 glaciers, American geologists for twenty or thirty years hesitated 

 to accept the new explanation, owing to the difficulty of con- 

 ceiving of a glacier so thick and so extensive that it could spread 

 its records continuously across uplands and valleys. The 

 unhappy effect of an inhospitable attitude toward a new theory 

 and new methods was clearly illustrated here during the period 

 from 1 841 to 1870, when the "glacial theory" was on probation. 

 Lively discussions of it, as reported in contemporary proceedings 

 of our scientific societies, betray the human tendency to judge 



