14 UNITED STATES GEOLOGICAL SUKVEY— TEKTIAKY FLORA. 



19. Ferruginous sandstone, barren 11 



20. White compact sandstone, in bank, and barren 28 



21. Hard white sandstone, in bank, witii Fucoids 10 



22. Soft white sandstone, with Fucoids 32 



23. Very hard block sandstone, barren 19 6 



24. Ferruginous sandy shale, with Fucoids 6 G 



25. White sandstone, barren 5 G 



2G. Ferruginous sandy shale, willi Fucoids 8 



27. Red shaly sandstone, with great abundance of Fucoids , . 3 



28. Hard white sandstone, in bank, \vith some Fucoids 12 



178 

 Between the last stratum^No. 27, and the Cretaceous black shale, no 

 nuiddy or brackish beds are seen. The transition is remarkai)Iy clear, but, 

 indeed, not more marked than it is between some beds of the Lignilic. The 

 characters of tiie lower group, one hundred and seventy-eight feet, from No. 

 17 to 28, are clearly described after the section, as follows: — 



1. Its general color is whitish-gray; so white, indeed, sometimes, that 

 the lower strata, seen from a distance, appear like banks of limestone. 



2. Though generally hard, it weathers by exfoliation under atmosplieric 

 influences, and its banks are thus molded in round undulations; and as it is 

 locally hardened by ferruginous infiltrations, it is often, too, concretionary or 

 grooved in cavities, so diversified in size and forms that sometimes the face 

 of the cliffs shows like the details of complicated architecture. 



3. It is entirely barren of remains of animals. 



4. On the contrary, from the lowest stratum to its upper part, it abounds 

 in well-preserved remains of marine plants or Fucoids, which in some localities 

 are seen even in the sandstone over lignite beds. 



5. In its upper part, the sandstone or the shales of this group are mixed 

 with broken debris of land vegetation, with which also Fucoidal remains are 

 found more and more abundant in descending. 



The disposition of the strata and their compounds is about the same on 



the otiier side of Purgatory River, opposite Trinidad, where the section is 



from top downward : * — 



Feet. 



1. Hard, ferruginous, shaly sandstone, with few remains of Fucoids, but 



abundance of debris of land plants 25 



• Annunl Report, 1872, p. 320. 



