Survey of the Concho Country. — Cummins-Lerch. 327 
mation in Texas. Their thickness has been estimated by us 
from borings and outcrops examined, to be 200 feet. No vol- 
canic action has disturbed the Permian strata in this country. 
Their composition speaks of shallow water beaches and quiet 
muddy seas accompanied by frequent oscillations of the sea 
bottom. We have been able to obtain only marine fossils and 
cannot say therefore with certainty that portions of this coun- 
try had been raised above the waves of the sea in this period. 
The change from the Permian to the Cretacic is abrupt. The 
earlier members of Mesozoic time, the Triassic and .Jurassic, 
are missing, and it must be concluded that either these forma- 
tions had never been deposited in this section or that after 
being laid down they were destroyed by subsequent erosion. 
The Cretacic commences with a loose sandstone in the 
lower strata, gradually changing to pure, hard limestone. 
SECTION OP THE PERMIAN. 
1 . Sandstone 4 feet. 
2. Yellow Sandstone, friable 2 " 
3. Sandstone, shaly 40 " 
4. RedClay 20 " 
5. Limestone, Fossiliferous 3 " 
6. Green Clav 8 " 
7. RedClay.' 6 " 
8. Green Clay 2 " 
9. Limestone 18 in. 
10. Whitish Clay 1 foot. 
11. Limestone 1 " 
12. Whitish 1 " 
13. Blue Clay 3 feet. 
14. Limestone 8 in. 
LIST OF FOSSILS. 
1. Goniatites baylorensis White. 
2. Medlicottia copei White. 
3. Orthoceras rushensis McChesney. 
4. Nantilus winsloun Meek and Worthen. 
5. Euomphalus subquadratus Meek and Worthen. 
6. Bellerophon crassus Meek and Worthen. 
7. Pleurophorus ? 
8. Myalina permiana Swallow. 
9. Aviculopceten ? 
10. Productus ? 
11. Murchisonia ? 
12. Fenestella ? 
Economic Geologr- 
Climate. — Conditions of the air, rainfall, soils and water. 
On account of the high altitude of this country, 2000 feet above 
the level of the sea, the pressure of the air considerably lessens, 
