974 REPORT OF NATIONAL MUSEUM, 1895. 



" This whole region may be iu one sense considered to be a mesa region, 

 since at one time the present mesa formation extended from coast to 

 coast, but at the present day the mesas are no longer continuous, and 

 erosion has disclosed an underlying or buried topography, whose 

 genera] features show considerable analogy with the more northern 

 region described by Lindgren. The mesa belt proper adjoining the 

 western coast is represented by a series of plateaus from 900 to 2,000 

 feet in elevation, separated by the deep canyon-like valleys of streams 

 that drain the interior. Owing to the soft, crumbling nature of the 

 beds, the escarpments are very abrupt, and the topography has some- 

 thing of the character of the Bad l^ands of the Great Plains. 



<'The coast or western range is represented by a series of isolated 

 peaks or ridges rising 1,000 or 2,000 feet above the general mesa level, 

 which are partly connected together by flat-topped ridges base-leveled 

 down to the average elevation of the highest portion of the mesa 

 region, but which in geological structure and composition belong to the 

 same system of uplift as the higher peaks. 



"East of this range lie the interior valleys, broad, level, or gently 

 sloping plains 10 to 15 miles in Avidth and with an elevation above 

 sea level of 1,800 to 2,200 feet, bounded and traversed by mesa-topped 

 ridges and with occasional sharp peaks rising out of them. These 

 interior valleys all drain to the Pacific through gaps in the western 

 range and rise gently to the eastward, the same gentle westward slope 

 being noticeable in the mesa-topped ridges. 



"On the eastern edge of these valleys, at a distance of about 10 to 15 

 miles from the Gulf Coast, a most sudden change in topographical 

 structure takes place. The broad, level plains, in which the drainage 

 courses are so shallow that their direction of drainage is with difficulty 

 recognizable, give place to deep, narrow, tortuous ravines, descending 

 a thousand or more feet within a few miles of the mesa-topped divide. 

 These ravines wind along a series of sharp Jagged peaks, which evi- 

 dently are the projecting summits of an older and partially buried 

 mountain chain. The eastern range is represented in part by the sum- 

 mits of this buried range, in part by a series of isolated table-topped 

 mountains rising to an elevation of 3,500 feet, which brings them above 

 the summits of most of the sharper peaks to the eastward. On the 

 immediate Gulf Coast is a gently sloping mesa, of varying width, at 

 the base of the eastern range. To the south of the region visited, the 

 buried mountains rise still higher than these table topped mountains 

 and send out spurs to the westward, which apparently cut off the 

 interior valley in that direction. To the north they do not rise above 

 the level of the interior valley, and the mesa-topped ridges sweep over 

 them, descending in a series of terraces or steps to the Gulf Coast. 



"The rocks, of whicli this eastern buried range is composed, outcrop 

 so frequently in tlie bottom of the interior valley that it is probable 

 that this valley rests in part upon a plateau-like shoulder of the buried 



