Carboniferous Glaclatlon, Etc. — White. 299 
features of the region. In the Potsdam tliere are superb beds 
of iron ore which, according to Prof. Everhart" of the univers- 
ity of Texas are equal in quality to the best Swedish. In the 
Cretaceous there are inexhaustible beds of the best Caen lime- 
stone, chalk and flints. In localities the conditions for 
hydraulic and Portland cements are exactly similar to those 
of the best European localities and unequaled in America. 
The black soils of the upper Cretaceous support one half the 
present population of Texas and produce two thirds the wealth. 
When proper country roads are built across it from the abun- 
dant road-making materials of the basaltic cones and lower 
Cretaceous limestones, it will be trebled in value. 
Such is a brief summary of the phenomena exposed by the 
erosion of the Colorado valley within forty miles of Austin. 
When it is added that there is no evidence that man has ever 
explored the deep canons, that the paleontology is almost 
untouched, that hardly any details of all these grand features 
have been recorded, one can but feel that the student of 
geolog}^ has here an inexhaustible field before him and the 
University of Texas a laboratory whose resources are not lim- 
ited by the generous hand of Nature. 
In future papers I shall describe the upper and lower thirds 
of the Colorado, and endeavor to show the surface geology 
and evolution of the present topographic feature of Texas. 
University of Texas, March, 1889. 
CARBONIFEROUS GLACIATION IN THE SOUTHERN AND 
EASTERN HEMISPHERES,— WITH SOME NOTES 
ON THE GLOSSOPTERIS-FLORA. 
By C. D. White. 
I. 
An apology is perhaps required for bringing before 
American geologists a subject the scene of which is laid, for 
the most part, in the opposite quarter of the globe ; and I 
should hardly venture to discuss such a question here, were it 
not for the certain and more or less direct effects on the cli- 
mate and life changes of America which must necessarily have 
attended a period of glacial cold in paleozoic time extending 
over a considerable part of the earth's surface. Should it 
once be proved that a glacial climate prevailed in extensive 
2 See Bulletin 4, Univeraitv of Texas. 
