62 Cretaceous. 



Eagle Pass is an open country, occupied by low swells of Cretaceous 

 limestone, thus merging into that character of country pertaining to 

 the region of central Texas. 



Prof. James Hall, to whom the minerals and fossils collected by the 

 Boundary Commission were referred for geological examination, com- 

 pared the Cretaceous of Texas and New Mexico with that of Nebraska 

 and the eastern states. He furnished the following section of the 

 successive beds comprising the Cretaceous formation of New Jersey, 

 which had been communicated to him by Prof. Geo. H. Cook for 

 comparison, to-wit: 



8. Greensand, Third or Upper Bed. [Probably of Eocene Age.] 

 This bed admits of a triple division, the central portion is nearly 

 destitute of fossils, while those of the upper and lower divisions are 

 mostly dissimilar. 



7. Quartzose Sand, resembling Beach Sand. 

 This bed is (so far as known), quite destitute of fossils. 

 G. Greensand, Second Bed. 



(«) Yellow limestone of Timber Creek. Characterized by 

 Eschara digitata, Montivaltia atlantica, JUTii^cleolites criicifer, 

 Ananchytes cinctus^ A. Jimbriatus, Morton. 



(5) A bed of nearly unchanged shells. Among the character- 

 istic fossils of this bed are Gryphcea vomer, G. convexa, and Tere- 

 hratula harlani. 

 (c) Greensand, etc. 



Cucullcea vulgai'is is the most characteristic fossil of the lower 

 division. 



5. Quartzose Sand highly Ferruginous throughout, and 

 Argillaceous in its upper parts. 



This ropk is sometimes indurated or cemented by oxyd of iron. 

 Exogyra costata, Ostrea larva, Belemnitella mucronata, Pecten 

 !z; I [Neithea) qiiinque-costatus ; and many other fossils mostly in 

 the condition of casts of the interior, or impressions of the exte- 

 rior. 



4. Greensand, First or Lower Bed. 



Several snbdivisions may be recognized depending on the char- 

 ^ acter of the marl, etc. Exogyra cosfata, Ostrea larva, Belemni- 

 tella mucronata, Terebratula sayi, [Gryphcea convexa and G. 

 mutabilis), Ostrea vesicular is. 



3. Dark Colored Clay, containing Greensand in Irregular 

 Stripes and Spots. 



Ammonites delawarensis, A. placenta, A. conradi, Baculites 

 \ ovatiis, casts of Cardium. 



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