126 RE VIE I VS 



Along the Big Sioux Valley, on the northwest boundary of Iowa, a 

 flood plain of modified drift associated with the moraines has an 

 average width of one and a half miles, as described in Vol. X of the 

 Iowa Geological Survey, and is only about lo feet above the present 

 relatively insignificant bottom land, which averages about a fifth of a 

 mile in width. Below the junction of the Big Sioux with the Missouri, 

 this flood plain of Wisconsin time continues with a width of 6 to 12 

 miles on the east side of the Missouri through the distance of 90 miles 

 to Council Bluffs and Omaha, having only the same slight altitude 

 above the river. Southward from the mouth of the Platte river, as I 

 think, the old Wisconsin flood-plain was lower than the bottomland 

 today, which has gained in thickness, rather than lost, ever since the 

 Ice age. Conditions requisite for silt deposition 30 to 50 feet above 

 the Missouri at Lansing, Kan., where a skeleton was discovered last 

 February under 20 feet of a deposit, which I regard as the original 

 lowan loess, appear thus not to have existed during the ensuing Wis- 

 consin stage of glaciation, nor during any part of the Postglacial 

 period. 



The antiquity of the Lansing man is, I think, to be measured by 

 about 12,000 years, or, at the longest, 15,000 years. But men are 

 known to have been living in Europe, and very probably they may also 

 have migrated to America, in the early part of the Ice age, or even 

 before it, that is, very surely as long age as 100,000 years. Therefore 

 the resemblance of the Lansing skeleton to the average type of our 

 American aborigines, called Indians, appears in no degree surprising 

 to one who believes that the creation of plants and animals has pro- 

 ceeded by the gradual methods of generic and specific development 

 which are collectively termed evolution. 



History of the Caribbean Islands from a Petrographic Point of View. 

 By Dr. Persifor Frazer. 



BIBLIOGRAPHY. 



Our knowledge of the geological history of the Antilles is still 

 very imperfect. Among the most important parts of the bibliography 

 of this subject are : 



"Topography and Geology of Santo Domingo," by William M. Gabb, 

 Trans. Am. Phil. Soc, Vol. XV, N. S. (1871). 



Observations and a Physico- Geological Dcscriptioft of the Regio7is of 

 Habana and Guanabacoa, by Salterain. Madrid, 1880. 



