MESOZOIC CUESTAS 



839 



to the Yorkshire coast and forms the CVttswold hills of middle 

 England with the Worcester lowland in front of it, and the other 

 in the chalk cliffs which extend in like manner from the Channel to 

 Flamborough Head, and forms the Chiltern hills of middle Eng- 

 land, the Oxford lowdand lying to the west of them. (Fig. 212.) 

 All of these topographic features are revived, being probably in 

 the second if not later cycle of erosion. The coastal plain of Ala- 

 bama, on the other hand, furnishes an example of a cuesta appar- 

 ently in the first cycle. The cuesta itself is formed by the Tertiary 

 strata of the coastal plain, the inface rising rather abruptly 200 feet 

 above the lowland and being locally known as Chunnenugga ridge. 

 On the broad upland dissected by short streams running down the 



Fig. 212. Stereogram of the Mesozoic coastal plain of central England: A, 

 old land of Palaeozoics (Wales) ; B, Worcester lowland on Trias- 

 sic sandstone; C, Cotswold hills or Oolite cuesta; D, Oxford 

 lowland on Upper Jurassic and Lower Cretacic clays, etc. ; E, 

 Chiltern hills or chalk cuesta; F, Tertiary coastal plain. (After 

 Davis.) 



inface (obsequent streams) lie the "hill prairies," the surface being 

 formed by a resistant limestone bed. This slopes south to the coast 

 and supports the "coastal prairies." Extensive pine forests also 

 grow on this surface. The inner lowland, which lies between the 

 inface and the old land formed by the rocks of the Appalachians, 

 is so level that rainfall drains slowly and roads are impassable in 

 wet weather. 'Tt is called the 'Black Prairie' from the dark color 

 of its rich soil, weathered from the weak imderlying limestone. 

 This belt includes the best cotton district of the state." (Davis- 



5-I35;) 



Minor Erosion Forms of Hori:^ontal Strata. Among these is 

 the mesa or flat-topped table moimtain, the surface of which is 

 formed by a resistant capping stratum. It is limited on all sides 

 by erosion cliffs, and it may constitute one of the last remnants of 

 a once widespread series of formations. The name "mesa" is also 



