214 
Teansactions Texas Academy of Science. 
Penkose, E. a. F., t^lE, 
few places, where natural conditions have protected the bed from atmos- 
pheric influences, it is found that the pyrite is especially abundant at the 
top of the glauconite bed and immediately below the overlying clayey sand. 
Here it occupies the same position as the laminated ore elsewhere, and 
is frequently associated with .sands and clays which often cont^n lignite.” 
P. 135. 
337. 
The Tertiary Iron Ores of Arkansas and Texas. 
Bulletin Greol. Soe. Amer., Yol. Ill, pp. 44-50. 1892. 
Contents: 'Distribution of the Ores. Nature of the Ores: Nodular 
Ores; Laminated Ores. Origin of the Ores. Conclusions. 
The general conclusions reached by the author are: 
“1. That the iron ores of Texas and Arkansas occur mostly in two 
positions in the Eocene series of the Tertiary, 
“2. That the ores were originally deposited in the form of oxide, oar- 
boiiate and sulphide contemporaneously with the associated strata, and 
that they were subsequently segregated mostly as carbonate and sul- 
phide. 
“3. That the ores as now found are the products of the oxidation of the 
carbonate and sulphide, the nodular ores being derived from the carbonate 
and the laminated ores from the sulphide of iron.” 
337a. 
Art. Manganese. 
The Mineral Industry, Its Statistics, Technology and Trade, 
1892. Vol. I. 
(Manganese in Texas), p. 335. N. Y., 1893. 
A brief notice of the deposits in the pre-Cambrian rocks of Alason, Llano 
and I'San 'Saba counties. 
338. Pond, Edward J. 
A Cretaceous Eiyer Bed. 
Science, Vol. 9, pp. 536-537. 1887. 
An attempt is here made to explain the springs at San Marcos, Hays 
county, Texpas, “where the San Marcos river rises full grown from the 
earth, with a steadiness of flow in marked contrast with the majority of 
Texas rivers.” The theory advanced, viz. : that the water supply is fur- 
nished by the Blanco river through the medium of an ancient Cretaceous 
river bed, is based upon an opinion ascribed to Professor R. T. Hill (Amer. 
Jour, of Science, III, Vol, 33, p. 29)., that there exists between the earlier 
Oretaceous strata of Texas and the superimposed rocks a plane of ‘non- 
conformity by erosion’ indicating a period of emergence between the two 
periods of the Cretaceous rock formation. 
