JULT 22, 1910] 



SCIENCE 



127 



during any period is measurable from some up- 

 raised peneplain level; its depositional equivalent 

 is usually much more diflBcult, and often impos- 

 sible, to estimate. 



When first recognized in its proper and vast 

 proportions, erosion by the winds in desert re- 

 gions appeared to have no downward limit corre- 

 sponding to the baselevel of general stream-ero- 

 sion. This aspect of the problem became the most 

 serious obstacle to its solution. More recently a 

 baselevel of eolio erosion has been found that is 

 as sharply defined as normal peneplanation. 



Inasmuch as general wasting of the land is 

 measurable either by the amount of erosion or by 

 the deposition products, but rarely by both at 

 least in the same geographic province, later geo- 

 logic time units are best estimated by the results 

 of the erosional processes and the earlier time- 

 intervals by sedimentation products. 



In southwestern United States the products of 

 the two opposed processes are in juxtaposition 

 and are in a remarkable manner sharply con- 

 trasted. The character of the erosion is not, 

 however, of the normal aqueous type, but of the 

 eolic variety. It is particularly noteworthy at 

 this time, on account of furnishing quantitative 

 data on the extent and rate of eolic activities 

 under climatic conditions stimulated solely by 

 aridity. 



This region of deserts has been already treated 

 as a direct product of eolation without material 

 interference from water action. The original sur- 

 face at the initiation of the arid cycle is assumed 

 to be essentially a peneplain extensively upraised. 

 The main remnant of the latter is regarded as 

 being the high Mesa de Maya in northeastern 

 New Mexico. This level is also approximately 

 the summit level of the majority of the Desert 

 ranges. Below it the present plains level lies 

 about 5,000 feet, the plains level being also about 

 the same distance above sea level. 



The depositional equivalent of the vast deflative 

 work throughout the region appears to be best 

 represented by the 5,000 to 8,000 feet of Tertiary 

 boraciferous clays and sands occupying the Santa 

 Clara, Mojave and Death basins of southern Cali- 

 fornia, and by the thick, but as yet unmeasured, 

 deposits of similar nature filling the great trough 

 of the Californian gulf. These deposits are now 

 believed to be mainly desert dusts blown into the 

 adjoining shallow seas. Since they are subdi- 

 visible into Eocene, Miocene and Pliocene sections, 

 as well as into several Quaternary terranes, quan- 

 titative data for the measurements of the several 



eolative phases of insolation, deflation and aero- 

 position are at once made available. 



Destruction of the Drumlins in Boston Harhor: 

 Geokqe C. Cuetis, Boston, Mass. (Read by 

 title.) 



The disappearance of the glacial islands of Bos- 

 ton harbor may be traced both by historical and 

 by geological records. Transitions from the most 

 perfect specimens of intact drumlin form through 

 successive stages of wasting away, from mere 

 nippings of their bases to last vanishing remnants 

 of till, and further to outlining boulders as wit- 

 nesses of former location, are exceptionally abun- 

 dant in Boston Bay. Typical cases are selected 

 from the harbor examples to illustrate the proc- 

 esses of marine erosion. 



The Coral Island, Bora Bora, and the Model as 



Illustrations of the Principles of Naturalistic 



Earth Relief: Geoege C. Cuetis, Boston, Mass. 



Bora Bora is a small island in the Society 

 group, southwestern Polynesia. It is surrounded 

 by a barrier reef of living corals. The island was 

 early studied by Lesson, Darwin and Dana, and 

 later by A. Agassiz. The writer made a detail 

 survey and a series of deep-sea soundings a mile 

 off the reef, about the entire island. The forma- 

 tions beginning with the deep sea, across the 

 island shelf, barrier reef, reef flat, etc., to the 

 central agglomerate peaks are taken up in order. 

 Evidence of movements of elevation and depres- 

 sion are cited in this and other members of the 

 Tahitian archipelago. 



The model of the island, now installed in the 

 coral room of the Agassiz Museum, for the con- 

 struction of which the survey was primarily 

 made, is considered as one of the pioneer works 

 in this branch of geology, for the possible light it 

 may be able to throw on the little-known prin- 

 ciples of naturalistic earth relief. 

 The Geographic and Geologic Character of tlie 



" Sahaiia" about Caicara, Venezuela: T. A. 



Bi:KDEAT, Turners Falls, Mass. No abstract 



received. 



Report of the Third Meeting of the Permanent 

 Commission of the International Seismological 

 Association held at Zermatt, Sicitzerland, 

 August 30 to September 3, 1909: Otto Klotz, 

 Ottawa, Canada. (Read by title.) 

 Rgsumg of meeting, with reference to several 



of the principal papers presented there. 



The Glacial Recession in Western New England: 

 F. B. Tayme, Fort Wayne, Ind. 

 During the retreat of the Labrador ice sheet 



