72 Tlte j\.iiierlcan Geologist. Aut'ust, i89i 
changed ; and that the 8tl pound stone f(,'ll on old turf, where the 
hist year's grass remained dry, and after the stone was taken out, 
portions of the grass carried down b}' it, adhered to the surface 
unburned. Besides one piece fell on a straw stack, and did not 
fire the straw. 
On the accompanying map of Winnebago Co. the positions of 
the Large fragments are indicated b}' their respective weights. The 
counties in which meteorites have fallen are indicated in the small 
count}' map of the state of Iowa. 
For assistance in preparing the map and for other information, 
specimens, etc. , we are indebted to the Messrs. Secor and Law, 
and the Messrs. Thompson of Forest City. 
ON THE CONTRAST IN COLOR OF THE SOILS 
OF HIGH AND LOW LATITUDES. 
BY W. O. CROSBY. 
The general contrast in color of northern and southern soils has 
attracted m^- attention for many j'ears ; and six years ago I sug- 
gested an explanation of this difference, which is evidently due to 
the condition of the ferric oxide, in a communication to the Boston 
Society of Natural History,^ from which several paragraphs may 
be advantageousl}' quoted as an introduction to the present paper. 
The prevailing difference in color between the soils of the North and 
South is an unquestionable fact, and must be familiar to many travelers ; 
and yet, but few geological writers have even mentioned it, and, so far 
as I can learn, no explanation of it has heretofore been proposed. In 
all latitudes, the most superficial detritus, the true agricultural soil, is, 
in a large measure, distinctly carbonaceous, or the organic matter has 
at least been sufficient to more or less completely discharge the brown, 
yellow, and red colors due to the ferric oxides. But in the surface soil 
to a considerable extent, and in the subsoil generally, the ferric oxides 
are still the predominant coloring agents. Now throughout the north- 
ern states and Canada the soils, where their colors can be ascribed to 
ferric oxide, are generally, almost universally, brownish or yellowish, 
but not distinctly red. The only important exceptions are where the 
red soil results from the disintegration of a red rock, or is itself geologi- 
cally old. Thus, the red color of the soil on the Triassic areas, and of 
the clays at IJrandon, Vermont, and Gay Head, does not belong to the 
present or any recent period, but is due to the peroxidation of iron in 
Triassic and Tertiary times. On the other hand, one of the most strik- 
ing features of the scenery of the southern states, especially for north- 
» Proceedings of the Boston Society of Natural History, Vol. XXIII., 
pp. 219—222. 
