July 27, 1906.] 



SCIENCE. 



117 



Nogales, frequent exposures of material re- 

 sembling in every way, except in its com- 

 ponent rocks, that of the terminal moraine of 

 New York and New Jersey. These exposures 

 were between Nogales and Imuris, occurring 

 frequently in a distance of some fifty miles, 

 and exhibited sections of till and boulder clay 

 with large angular rock fragments and the 

 occasional partial stratification characteristic 

 of various portions of the terminal moraine 

 in the northeast. 



Having then no opportunity to verify these 

 observations, they were briefly noted, to be 

 amplified on some future occasion. 



During the months of April and May of 

 the present year, a further opportunity was 

 afforded to traverse the same country and 

 secure additional data bearing on the phe- 

 nomena mentioned. 



These last observations have convinced me 

 that there is, in the vicinity of Nogales, both 

 in Arizona and in Sonora, and for a number 

 of miles north and south of the national 

 boundary, an area of some width in which 

 land ice transportation has been operative and 

 has resulted in the formation of morainal 

 deposits of various types. 



A complete absence of detailed maps in 

 northern Sonora makes it difficult, without 

 extended study in the field, to form any gen- 

 eralizations concerning the centers of accumu- 

 lation from which the glacier or glaciers may 

 have flowed. 



In Arizona, the publication, during 1905, 

 of the Nogales, Patagonia and Tucson quad- 

 rangles affords an opportunity to locate the 

 more important phenomena observed and de- 

 termine the possible sources of ice action. 



Some ten miles north of Nogales rises from 

 the general level of the surrounding desert 

 country a high range known as the Santa 

 Rita Mountains. At the desert level, which 

 is about 2,700 feet, this range has a base ap- 

 proximately thirty miles long and from eight 

 to fifteen miles wide. Its highest peak has an 

 altitude of 9,400 feet and a considerable area 

 of the range (perhaps twenty square miles) 

 is above the six-thousand-foot level. Within 

 a mile or two of the southeastern base of the 



range passes the Sonora Railway, which, here 

 as in Sonora, by its numerous cuts and bor- 

 row pits, gives an opportunity to study the 

 composition of a formation which has all the 

 characteristics of a moraine deposit, but which, 

 in the absence of sections, a casual observer 

 might pass by as a terrane of volcanic material 

 rotted in place. 



In connection with the structure exposed 

 by the sections, one recognizes at many points 

 the rolling topography and pitted surface of 

 a moraine. At one or two points are observed 

 depressions, similar to those which in the 

 north have been formed by stagnant ice, sur- 

 rounded by kame terraces and their concord- 

 ant phenomena. One of these is just south 

 of Huachuca Station. 



About three miles south of Nogales is a 

 very extensive borrow pit, formed in the con- 

 struction of the railroad, in which has been 

 left a number of large rock fragments which 

 are clearly of transported material. Among 

 these, the writer noted several blocks of dark 

 blue limestone which did not belong to the 

 crystalline terrane beneath and which had 

 evidently been transported some distance. 



A marked difference between the transport- 

 ed material here and that in the north lies in 

 the comparative absence of large boulders, for 

 none were seen to exceed about two feet in 

 diameter. This is probably due to the char- 

 acter of the volcanic rocks and their manner 

 of decay. A cliff of andesite or rhyolite does 

 not in Arizona or Sonora seem to yield talus 

 fragments of as large size as a cliff of granite 

 or gneiss in New York. 



The total extent of these glacial formations 

 could not be determined without an extended 

 reconnoissance which the writer had not time 

 to make, but they are apparently limited to 

 the vicinity of the higher mountain ranges. 

 About twenty miles west of the Santa Rita 

 Mountains, between Sopori and Arivaca, on 

 the west of the Atascosa Range, is a long 

 stretch of low hills and rolling country, trend- 

 ing southwesterly, which has a morainal ap- 

 pearance; but in the absence of sections no 

 decisive conclusion was reached. 



In northern Sonora, near the valley occu- 



