Record of Geology of Texas, ISSY-ISOG. 
155 
Hill^ Egbert T. 
and Southwest Texas .they hecoime the prevalent surface fiormations. In- 
crease in hhickneS'S. ^Between Arfeadelphia and the Pasezoic area of Cen- 
tral Texas there are 5000 feet of Upper and Bower Cretaceous deposits. 
A Summary of Cretaceous Poirmations: 
The Upper, or Black Prairie Formation -.(Gulf Series). Made up of 
five subdivisions. Thickness of each, and localities of oocurrenee. 
The Lower, or Grand Prairie Formation (Comancho Series). Made up 
of nine subdivisions- Thickness of each and loealities of occurrence. 
‘‘The immediate ohjects of .this paper are to call attention to (1) the 
beds of the uppermost or glauconitic division of the Upper Oretaceons, (2) 
to the i,mportant light they throw upon the Cretaceous beds of the Gulf 
and Atlantic States east of the Mississippi, and (3) to the complete non- 
conformity by erosion and deposition that exists between them and the 
basal beds of the Southern States Tertiary.” 
The sequence of sediments during the Upper Cretaceous subsidence and 
emergence. The Glauconite beds. The Texas exposure on the Trinity in 
Anderson County. The Exogyra pondero'sa Marls.- The Glauconite beds 
of New Jersey. Lamellibranchiate species common in America to Arkan- 
sas, Texas, Mississippi and the Lower Marl bed of New Jersey. None of 
the characteristic fossils of the New Jersey Cretaceous above the Lower 
:Marl bed occur in the Arkansas-Texas Cretaceous. The conclusion on 
paleontologic and lithologic grounds is “that .the upperimost beds of Arkan- 
■ sas are the southwestern representative, perhajDS the direct continuation, 
of the lower marl beds of the New Jersey region, an opinion which is 
strengthened by the stratigraphic evidence, which shows a complete un- 
conformity between the uppermost Cretaceous of Arkansas and Texas north 
of the Rio Grande. Also, that .a large part of the glauconitic beds were 
eroded, and their debris redeposited in the Eo-Lignitic or basal beds of the 
Southern iStates Tertiary.. The iron ores of the Southern Tertiary are 
primarily derived from this source- This fact has been determined by 
-most careful observation on the part of Mr. R. A. F. Penrose, Jr., and 
the writer, in Texas and in Arkansas. The contacts in the latter region are 
described in full in my Arkansas Report, while those in Texas will soon 
be published in Mr. Penrose’s report to the State Geologist, Mr. E. T. 
Bumble.”' 
Geography of the Texas Cretaceous. Suggestion as to the use of the 
term “Glauconitic.” 
See Amer. Naturalist, Vol. 24, p. 769. 
216 . 
'Classification and Origin of the Chief .Geographic Features of 
the Texas Eegion. I. 
Amer. Geologist, Vol. Y, pp. 9-29. Minneapolis, Jan., 1890. 
Contents: (Introduction.) The Plains of Texas. The Coast Prai- 
ries. The Sandy Lignitie, or Forest Area. The Black Prairie Region. 
The B.al cones. The Shumard -Knobs. The Grand Prairie. The Central 
Denuded Region. Older iRock Regions.- The Red Beds. The Abilene 
Country. The Gypsum country. The Llano Estacado or Staked Plains, 
