Da al ie i ba i aa ae alu Ss 
Se ee Le ES AER ery se ae 
n 
excavating force of the stream 
Geology and Natural History. 145 
covers a large part of North America, north of the Ohio, and exist- 
ing i i 
ar 
ornot); and thus such flats, while the sea has its present level, 
a single river at all heights, from a few feet above 
Stream and being such very nearly as actually exist between flood 
level and low-water level. 
art of the continent be raised 50 feet, the abrading or 
s would be increased; the low- 
Water channel would be accordingly deepened by abrasion, and a 
Ww ground or lower flat would also be produced with the 
t the nature of the bottom, etc.; thus with a single eleva- 
tion of 50 feet, terraces may be made at all heights above the se 
50 feet to or more, according to the height of the head- 
j Incidental to such a system of river changes. They are evi- 
shees that the stream has excavated its bed to a lower level 
Team in its diferent parts, an : : 
a have put a limit to omaiaten or occasioned intervals of 
on, 
Glaciers,—The Philosophical Magazine for June, (pp. 485- 
8) contains a translation of a valuable paper on Glaciers from 
ne oendorii’s Annalen, by Arserr Hum of Zurich. T he follow- 
"8 Paragraphs are from pages 495, 496. 
AM. Jour, Sci.—Turrp Serres, Vor. 1, No. 8.—Aveust, 1871. 
& 10 
* 
