May 1, 1908] 



SCIENCE 



695 



one to determine fairly well the positions of 

 the retreating ice front at these particular 

 places, the deposits are almost wholly confined 

 to the valleys, not being traceable across the 

 intervening ridges. However, a consideration 

 of all the factors affords a basis for their cor- 

 relation as marking thirteen stages of halt in 

 the recession of the ice front across the 30- 

 minute quadrangle. These seem to show a 

 probable gradual development of a broad re- 

 entrant over the Worcester County plateau 

 with lobes lagging behind in the Connecticut 

 Valley and on the lower ground to the east- 

 ward, so that in the western part the retreat 

 was from southeast to northwest, and in the 

 eastern part from southwest to northeast. 



The phenomena noted above appear to have 

 been formed immediately in connection with 

 the retreating ice front. Nothing was ob- 

 served indicating that the elevation was lower 

 than at present or that there was an incursion 

 of the sea up the valleys following the de- 

 glaciation. 

 Notes on Recent Changes in the Bogoslof 



Islands: Philip S. Smith. 



In 1900 Merriam summarized the changes 

 that have taken place in the Bogoslof Islands 

 up to the time of the Harriman Expedition 

 of 1899. Since that time two new volcanoes 

 have been formed and one of these later peaks 

 has disappeared. Many of the stages in the 

 rapid changes noted in the islands have been 

 mapped by different observers, especially in 

 the critical years 1906 and 1907. Maps 

 made by Dunn and Stromburg in 1906 

 were exhibited, but the most interesting 

 series were maps made by Camden, July 4, 

 1907, Jaggar, August 7, 1907, Camden, Aug- 

 ust 11, 1907, and October 16, 1907. The two 

 last maps represented the conditions approxi- 

 mately a month before and a month after the 

 disappearance of McCuUock Peak, the new 

 volcano which was formed between September, 

 1906, and July, 1907. Fragments of the 

 ejectementa collected by the Revenue Cutter 

 Service, on examination showed at least two 

 distinct kinds of rock; one an andesite with 

 both hornblende and augite, a rather basic 

 feldspar and an abundance of volcanic glass; 



the other showed a granular rock similar to a 

 diorite with essentially the same minerals as 

 those of the andesite, but crystallizing with a 

 distinct hypidiomorphic texture. None of the 

 specimens were collected from ledges and it is 

 not known whether or not the diorite is from 

 a fragment riven from the walls of the con- 

 duit and thus brought to the surface. The 

 presence of granitoid rocks on the southern 

 margin of the Aleutian chain, however, sug- 

 gests that the basement on which the recent 

 volcanics have been poured out is in many 

 places a coarsely crystalline granular plutonic 

 rock. No flows of lava were noted in connec- 

 tion with any of the recent eruptions on the 

 Bogoslof islands. 



Philip S. Smith, 



Secretary 



THE PHILOSOPHICAL SOCIETY OF WASHINGTON 



The 649th meeting was held on April 11, 

 1908, President Bauer presiding. Mr. Bailey 

 Willis, of the U. S. Geological Survey, pre- 

 sented by invitation a very interesting paper 

 on " The Mobility of the Lithosphere." 



The address of the last retiring president 

 of the society, Mr. John F. Hayford, was on 

 " The Earth a Failing Structure." In it Mr. 

 Hayford discussed the relations of weight, 

 mass and stability of the earth, and gave phys- 

 ical and geological evidence in favor of the 

 view that the earth yields more or less con- 

 stantly to the internal stresses due to gravita- 

 tion. Mr. Willis took up this theme along the 

 lines of geological evidence and presented the 

 conclusion that no considerable mass of the 

 lithosphere has been in a state of rest, that is 

 of static equilibrium, within any period known 

 to geological history. 



Referring to the distinction initially made 

 by Powell and Gilbert between epeirogenic 

 and orogenic movements in the earth's crust, 

 the speaker first showed a series of lantern 

 slides illustrating different geographic condi- 

 tions of North America from late pre-Cam- 

 brian to the present time. These charts are 

 necessarily, in the present state of the science 

 of paleogeography, of a provisional nature, 

 and subject to material modification, so far 



