40 NEW YORK STATE MUSEUM 



ward into the Mesozoic interior sea. There were probably other 

 consequent rivers, whose location may be in part indicated by some 

 of the valleys now occupied by the Finger lakes of New York. 

 Subsequent streams, flowing along the strike of the beds and capa- 

 ble of accomplishing much erosion by undermining the resistant 

 capping beds of the escarpments, continued to widen the longi- 

 tudinal (i. e. eastwest) lowland areas, while the transverse valleys of 

 the consequent streams remained relatively narrow. 



The topographic relief feature produced by this normal develop- 

 ment of drainage on a young coastal plain consisting of alternating 

 harder and softer strata, has been named a " cuesta 'V and may be 

 briefly defined as an upland belt of slightly inclined coastal plain 

 strata^ with a surface gently sloping toward the newer shore, and 

 a steep escarpment, or inface, fronting a low belt, or inner low- 

 land, which separates the cuesta from the old-land upon which its 

 strata formerly lapped. The existence of the cuesta form is usually 

 due to a more or less resistant stratum overlying a less resistant 

 one, as, for example, the limestones overlying the upper Medina 

 shales. The inface of the cuesta is continually pushed back by the 

 undermining subsequent streams, aided by atmospheric attack, and 

 thus the belt of low country, lying between the cuesta and the old- 

 land, is continually widened, while during the same time the valley 

 of the transverse consequent stream which carries out the drainage 

 increases comparatively little in width. It must be remembered 

 however that the lowland can never be deepened below the depth 

 of the valley of the consequent stream which carries its waters 

 through the breach in the cuesta. 



While the main drainage of this region was undoubtedly south- 

 westward by consequent streams, which flowed through the cuesta 

 in gorges, and by subsequent streams flowing into the former, and 

 occupying the inner lowlands, short streams, flowing toward the 

 old-land, down the inface of the cuesta, were probably not uncom- 

 mon. These streams began to gnaw gullies back from the inface 



^ Davis, W. M. Science. 1897. New series. 5:362; also Textbook of 

 physical geography. 1899. p. 133. Pronounced kwesta, a word of Spanish 

 origin " used in New Mexico for low ridges of steep descent on one side and 

 gentle slope on the other ". 



