Vol. VII] DICKERSON & KEW— FAUNA MEDIAL TERTIARY 127 



ern end of the district, the contact of the eruptives with the yellow clays is 

 well shown. 



Lying four to six miles east of San Rafael there is a range of hills 300 

 to 400 feet in height, composed of alternating beds of yellow clays and 

 clayey limestones carrying poorly preserved moUuscan forms together 

 with great numbers of Cristellaria, corals and some Nunimulites. Among 

 the corals collected here, Dr. T. W. Vaughan determined Favosites (?) 

 polygonalis Duncan, Goniastrea antiguensis Duncan, Acropora (?), sp., 

 Orbicella, n. sp., and Goniopora, sp., very similar to or identical with an 

 Antiguan species. These, he says, indicate an Upper Oligocene horizon 

 about equivalent to the Chattahoochee of Georgia. 



Around the San Jose de las Rusias Ranch the beds which are exposed 

 show considerable disturbance. Immediately at the ranch the beds, which 

 are fossiliferous sandstones, dip northwest at a high angle. Northeast of 

 the ranch a hill 60 feet high shows beds of yellow clay overlain by hard 

 calcareous sandstone which weathers into rounded masses. A great number 

 of corals occur within the clays and in the sandstone. Dr. Vaughan re- 

 ports Orbicella cellulosa Duncan, and Meandrina, n. sp., from this locality. 

 A short distance north of this hill is another in which the basalt has come 

 up through the Oligocene beds which are here impregnated with asphalt. To 

 the east of the ranch, some few miles, there is a range of hills 400 feet high 

 capped with the Coquina, and lying to the east of the range another vol- 

 canic hill. North of the Soto la Marina the same clays and limestones 

 occur and east of the Salitre Ranch the same Orbicella was found as that 

 occurring southeast of San Rafael, together with specimens of a new 

 genus of the fungid corals. At and around Salitre were found three 

 species of echinoderms {Agassisia clevei Cotteau, Clypeaster cubcnsis 

 Cotteau, Clypeaster, sp. b occur at Localities x24 and x25. R. E. D.), the 

 only ones so far found in beds we have recognized as Oligocene. 



A range of hills known as the Martines which are similar to those 

 seen east of San Jose de las Rusias and of about equal height is found here 

 extending from Salitre southward nearly to the Soto la Marina River. 

 Along the Conchos River the exposures of the Oligocene are of beds 

 higher in the series than the bulk of those of San Jose de las Rusias, being 

 represented in that region by the Pecten beds which lie along its extreme 

 eastern border. In the valley of the Conchos the greenish clays and soft 

 sands with their beds of gj'psum, which are part of the Frio, are found as 

 far east as Tepetate and forming the body of the hills lying directly north. 

 Beds of the Oligocene are found not only overlying these beds at this 

 point, but stretching several miles westward, showing a clear overlap to 

 lower beds of the Eocene section. 



What seem to be the lowest beds of the San Fernando section were 

 found three miles west of that town, and consist of cross-bedded gray 

 sandstones with a thickness of 60 feet. Half a mile east the beds form a 

 series of falls in the river and we have the following section : 



Feet 



Conglomerate 4 



Cross-bedded sandstone indurated and with bands of fossils 70 



Yellowish sandstones with fossils 3 



Gray sandstones weathering in holes, few fossils 4 



The cross-bedded sandstone carries a great number of a large Pecten, 

 which are well preserved, and, as it appears to be a well-marked horizon, 

 we have called it the Pecten bed. (Locality x4. Pecten condylomatits 

 Dall, Pecten levicostatus Toula, Pecten gatunensis Toula occur here. R. 

 E. D.) It is immediately overlain by beds of sandy clay with fragments 

 of shells, a well-preserved large gasteropod, and numerous claws of a 

 crustacean. 



