Dr. C. A. White has collected some fossils near Santo Tomas, but they have not been determined. These specimens, also those from the coal shaft, are poorly preserved.
The dip at Santo Tomas, according to information furnished by Mr. Davis and based upon mine workings, is 2° N. 40° E.
From the sandstone which immediately overlies the coal Mr. Davis had collected several fossil leaves, which he presented to us. Professor Knowlton has examined them, and finds a new species of Juglans, and another species which could not be determined.
From the clays just above the coal (locality No. 280) Mr. Stanton collected some leaves and a Unio. The leaves were too poor for identi fication. Professor Knowlton states that one looks like a Ficus; he is also of the opinion that the plants from Santo Tomas have a Laramie facies, but does not feel justified in expressing an opinion as to whether they are from the upper or the lower Laramie.
The following is a resume of the section of the Eocene based on observations and the data accumulated:
Resume of section of Eocene.
The fossils reported by Pen rose * from Webb bluff probably occur
below the Carrizo sandstone.
It is evident that the coarse sandstone seen at and near Chupadero
ranch has not been reached in the prospect drill at Carbon, near Santo Tomas. It is difficult to correlate the records of the drill at Pilot ranch with the Santo Tomas section. Lithologically the section resembles very much the coal-bearing portion of the Santo Tomas section. In the Pilot ranch drill hole the lower sandstone has not
The disturbance in the dip at Santo Tomas, together with the
extreme similarity in lithologic character of the beds, introduces such complications that reliable estimates of the thickness of the beds and the determination of the number and relative position of the coal
seams can not be made until the area has been studied in detail. The following is taken from Penrose's description of the section
along the Rio Grande from W rebb bluff to Laredo. 2 The section of
Webb bluff has already been given.
1 First Ann. Kept. Geol. Survey of Texas, 1890, p. 41.
2 First Ann. Kept. Geol. Survey of Texas, pp. 42 and 43; see also Dumblc's Report on the brown coal and lignite of Texas: Geol. Surv. of Texas, 1892, pp. 137-139.
Feet. 5. The coal beds and the clays and sandstone immediately overlying them were the highest beds seen. Between the two coal seams is a bed of fossils not yet determined 190 4. Below the coal beds is a series of alternations of clay, shales, and sandstones
of a thickness of at least 400
3. A series of fine-grained micaceous sandstone 300
2. The coarsely crystalline Carrizo sandstone, with a thickness of at least 150
1. Bluish clays —ascertained by a well boring, below which are more sandstones