IOWA ACADEMY OF SCIENCES. 227 



CUESTA TOPOGRAPHY OF THE CRIMEAN PENIN- 

 SULA. 



BY CHARLES R KEYES. 



(\bstract.) 



At the last meeting of the Academy I discussed briefly some 

 aspects of the geographic development of the Crimea and the 

 northern borders of the Black sea. Since that time certain of 

 the photographs obtained by those who took part in the geo- 

 logical excursions following the International Congress of 

 Geologists, have been received. It is to one of these especially 

 that I now wish to direct your attention. It shows very clearly 

 certain phases of the surface relief of which mention was made 

 last year, and in a way that is rarely ever exhibited to such a 

 great advantage or to such an extent. The photograph is one 

 taken by Mr. R. T. Mallet of Loudon, who was a member of 

 the party. It is through his kindness I am now able to pre- 

 sent it to you. 



The photograph (plate vii) is, I think, the best one ever 

 secured showing what modern geographers term Cuesta relief. 

 The word cuesta is a recent American acquisition from the 

 Spanish. It is a common word, used in southwestern United 

 States and Mexico to express the same idea that we do by step- 

 and-platform topography. The short, simple and expressive 

 word has been seized with avidity and has been used widely in 

 place of the longer phrase. 



The development of the Caesta type of surface relief is, 

 briefly, this: A region of slightly tilled strata composed of 

 alternating hard and soft beds is planed off or worn down to a 

 peneplain, or a base-level plain. This grade-plain is one of 

 faint relief, lying slightly above sea level. When such a 

 region again suffers differential uplifting, the agencies of ero- 

 sion actively begin to work anew Long lateral valleys are 

 soon opened out in the soft strata along the strike of the rocks 

 or at right angles to the direction of greatest dips. These 



