Fkbeuauy 6, 1903.] 



SCIENCE. 



225 



Studies in the Glaciation of the Berkshire 

 Hills, Massachusetts: Frank B. Taylor, 

 Port \Yayne, Ind. 



The Berkshire Hills lie within the area 

 covered by the retreating Hudson VaUey 

 lobe of the Labrador ice-sheet. The re- 

 treat of the ice-front across Berkshire 

 County was from southeast to northwest 

 and the trend of the front was northeast 

 and southwest, the apex of the lobe resting 

 on tlie central axis of the Hudson Valley. 

 In the lower, less mountainous region near 

 the Hudson River, the moraines and border 

 drainage features, though faint, are con- 

 tinuous, so that the positions of the ice- 

 front at its several halts are traceable 

 continuously. In Berkshire County con- 

 tinuous tracing is not possible, the boi'ders 

 there being marked by fragmentary ter- 

 minal and lateral moraines, mostly very 

 slender, and by remains of border drain- 

 age. The extremely serrate character of 

 the ice margin at each halt, coupled Avith 

 the frequency of the halts, makes interpre- 

 tation difficult. The average interval be- 

 tween successive recessional moraines is 

 about three and one half miles. The paper 

 wa.s devoted mainlj- to a discussion of the 

 method of interpretation, showing, first, 

 that, by the circumstances of the recession 

 across this county, the moraine marking 

 each halt of the ice-front may be safely 

 regarded as an individual, separate and 

 distinct from the moraines of earlier and 

 later halts; and, second, that interpreta- 

 tion on this assumption unifies and ex- 

 plains the morainic phenomena of Berk- 

 shire County satisfactorily. 



The Geological Age of the West Indian 

 Volcanic Foundation: J. W. Spencer, 

 Toronto. 



From personal explorations the author 

 has found that the whole Caribbean pla- 

 teau is underlain by an igneous basement 

 of pre-Tertiary age. This foundation oc- 



curs not merely beneath the older Tertiary 

 limestone, but also on those islands where 

 such have not accumulated, or have been 

 removed by denudation, and are now sur- 

 mounted by volcanic ridges. The igneous 

 formations have been analyzed, and their 

 relationship to the later fossiliferous de- 

 posits show that the volcanic activity was 

 renewed about the close of the Pliocene 

 period, and has continued intermittently 

 since that time. And it also seems prob- 

 able that there was a long quiescence dur- 

 ing the greater part of the Tertiary period. 



The Geologic and Physiographic History 

 of the Lesser Antilles: Robert T. Ha,L, 

 U. S. Geological Survey. 

 The author stated that the Windward 

 chain of islands from the Anegada Passage 

 to the South American coast consisted of 

 three distinct types of islands: (1) Those 

 of the Virgin chain, which were Antillean 

 in their relationships; (2) those of the 

 Caribbee chain, which were constructional 

 volcanic forms; and (3) islands of the 

 Trinidad type, which were detached por- 

 tions of the South American continent. 

 Besides these types there is the semblance 

 of an outer circle of islands, including 

 Antigua, Grande Terre (Guadeloupe) and 

 Maria Galante, consisting of marine sedi- 

 mentaries veneered upon old volcanic piles. 

 Barbados is in a class by itself, with 

 probably South American relations. Vul- 

 canism has prevailed in the Caribbean 

 islands since Ci'ctaceous time, and the vol- 

 canic ejecta have consisted essentially of 

 horneblende-andesites throughout. Physio- 

 graphically the islands are of several dis- 

 tinct types. The Caribbee Islands proper 

 are strictly constructional forms modified 

 somewhat by rainfall erosion, and trun- 

 cated around the edges by marine erosion. 

 The changes of level have been more or 

 less epeirogenic, but never, at least since 

 Jurassic times, has there been any connec- 



