328 Scientific Intelligence. 



of a most interesting period in the geology of the western United 

 States. This is a region characterized, as the author remarks, by 

 a dry climate, interior drainage, and a peculiar mountain system ; 

 while its later history includes changes of climate and drainage 

 with volcanic eruption and crustal displacement. All of these 

 points are clearly brought out in the history of Lake Bonneville. 



After a discussion of the topographic features of lake shores 

 in general, with respect to the formation of cliffs and terraces by 

 waves and shore currents, and related points, the author goes on 

 to a description of the shores of Lake Bonneville, which, briefly 

 summarized, are as follows : There is first in order of position, 

 the Bonneville shore-line, 1000 feet above the present Great Salt 

 Lake and embracing an area of nearly 20,000 square miles, 

 synchronous through its whole extent ; 375 feet below this is 

 the Provo shore-line, the most strongly marked of all, when the 

 lake area was about 13,000 square miles ; between the two are 

 the Intermediate shore-lines, while below the Provo, the slopes 

 exhibit lake sediments with occasional shore-lines, and of these 

 the Stansbury is the most prominent. The chronological order 

 of these shore-lines is : (1) Intermediate, (2) Bonneville, (3) 

 Provo, (4) Stansbury. During the period of the formation of 

 the Intermediate embankments the water surface oscillated up 

 and down, finally reaching its highest stage when the Bonneville 

 shore was formed. At the level of the Bonneville shore-line, the 

 lake had an outlet to the north through the Cache valley and 

 Red Rock Pass into the Snake River valley. The sill of this out- 

 let was alluvium, but when washed out to the limestone ledge, 375 

 feet beneath, the lake was throughout lowered to this level and 

 this marks the position of the Provo shore-line. 



A description in detail of tbe character of the Bonneville beds, is 

 followed by a summary of the history of the basin. Starting from 

 the previous arid period, the first rise of the lake was long con- 

 tinued and was without overflow ; during this period a thick and 

 aluminous yellow clay was deposited. Then followed a second 

 rise of 90 feet higher, causing overflow to the north, as stated 

 above, but this was of short duration and resulted only in the 

 deposition of a thin calcareous white marl. As the drying of 

 the lake went on the basin was divided into a dozen independent 

 basins of which that of the Great Salt Lake is the largest. Since 

 1845 there has been a repeated rise and fall through a range of 

 ten feet, and a very interesting part of this monograph is con- 

 cerned with the discussion of the character and causes of these 

 later changes. Connected with the changes in the level of the 

 Lake Bonneville, as also with the parallel history of Lake Lahontan 

 is the glaciation in the neighboring mountains, and the facts 

 observed lead to the conclusion that the Pleistocene lakes of the 

 western United States were coincident with the glaciers of the 

 same district and were produced by the same climatic changes. 

 Besides developing the history of the lakes }3roper, ot which this 

 is a brief outline, an account is also given in the closing 



