840 



PRINCIPLES OF STRATIGRAPHY 



sometimes applied to a tableland cut out of a peneplaned region, 

 where the strata are disturbed or where the material is crystalline 

 rock. Its restriction to an erosion remnant of horizontal strata is 

 desirable. When the mesa has been reduced to small dimensions 

 so that it has no longer an extended flat top — the name butte ap- 

 plies, though here again the designation is not always uniform, for 

 the name is applied to hills of varying origin, even to volcanic cones. 

 Restriction here would serve the cause of accuracy and precision. 

 A tcpee-butte is a conical erosion hill, so named from its resem- 

 blance to the Indian wigwam or tepee. Tepee-buttes abound in the 

 region east of the Front Range in Colorado, where they are formed 

 by the resistance to erosion of a core of organic limestone which is 

 surrounded by soft, easily eroded shale. These have been described 

 and figured in Chapter X and the student is referred to the paper 

 by Gilbert and Gulliver there cited. 



B. EROSION FEATURES IN DISTURBED STRATA. 



^ 2. The Monocline. 



When the old land, together with the edge of the coastal plain 

 lapping onto it, suffers an uplifting which does not affect the coastal 

 plain strata at a distance from the old land, a monoclinal structure 



Fig. 213. Diagrams illustrating the formation of a simple hog-back (a, b). 

 and of complementary hog-backs (c, d). 



is given to the edge of these coastal plain strata. On these up- 

 bending ends of the strata erosion will proceed in much the same 

 manner as in the normal coastal plain, and a topography com- 

 parable to the cuesta and differing from it only in the greater inclin- 



