Geology. 353 



of the evidence showing the relation of ore deposition in the 

 fissures to the wall rock. j. b. 



4. Some Characteristics of the Glacial Period in non-glaci- 

 ated Regions / by Ellsworth Huntington. Bull. Geol. Soc. 

 America, vol. xviii, pp. 351-388, pis. 31-39, 1907. — In this paper 

 the author calls attention to the fact that the glacial period was 

 characterized by glaciation over a relatively small portion of the 

 earth's surface, and that minor changes of this character might 

 occur without actually reaching glacial conditions. Glaciation 

 has represented rather local and extreme effects, but the climatic 

 changes which resulted in glaciation affected all parts of the 

 earth and left their stratigraphic records in the form of fluvial 

 and lacustral deposits. The phase of glaciation has almost 

 monopolized scientific attention, however, and the other changes 

 have not received the study which their broad distribution war- 

 rants, due to the striking evidences of glacial action and the fact 

 that geology has taken its rise in that part of the world which 

 suffered the most extreme glaciation in recent times. 



The paper is important in calling attention to the fluvial and 

 lacustral phenomena of the recent glacial period in the basins of 

 central Asia and in showing that these are as definite in their 

 nature as the glacial and interglacial deposits on the two sides of 

 the North Atlantic Ocean. The record is, further, likely to be 

 more complete, since the maximum glacial advance destroys 

 nearly all of the previous deposits and the resulting record is one 

 in which the oldest evidence belongs to the farthest ice advance. 



The author points out also the rhythmic nature of the Pleisto- 

 cene climatic changes and as terms of wider application than 

 glacial and interglacial suggests from the analogy of poetic 

 rhythm the words arsis and thesis. A glacial period is thus a 

 strophic period, consisting of arsial and thesial stages. j. b. 



5. Origin and Significance of the Mauch Chunk Shale / by 

 Joseph Barrell. Bull. Geol. Soc. America, vol. xviii, pp. 449- 

 476, pis. 49-52, 1907.— The first half of this paper gives the 

 results of field observations upon the Mauch Chunk formation, 

 accompanied by half-tone reproductions from photographs. The 

 mineralogical and structural features and the nature of the plant 

 fossils are described in detail. In the second half are discussed 

 the conditions under which such structures and plant remains are 

 buried at the present time. From this it is concluded that while 

 a marine phase occurs in south-central Pennsylvania, that in the 

 northeastern portion of the state the formation consists domi- 

 nantly of fluviatile beds accumulated under a semi-arid climate. 



6. Water Resources of the East St. Louis District ; by 

 Isaiah Bowman - , assisted by Chester Albert Reeds. Bulletin 

 No. 5, Illinois State Geological Survey, 1907. Pp. x + 128, pis. 

 4, figs. 11. — This report opens with an interesting discussion of 

 the economic features which have determined the .flood-plain of 

 the Mississippi at East St. Louis as a manufacturing site. The 

 marginal upland shows combinations of normal topography with 



