GEOLOGY AND NATURAL HISTORY OF LOWER CALIFORNIA. 973 



ward, as far as examined by the writers, the mesa structure is charac- 

 teristic of the Pacific Coast, the table lands rising to a height of 1,000 

 to 2,000 feet at comparatively short distances from the sea, and pre- 

 senting bold bluffs of soft horizontally stratified beds, often capped by 

 lava flows, which are evidently wearing away rapidly under the erosive 

 action of waves. 



"Lindgren, as a result of his observations in the vicinity of Ensenada 

 de Todos Santos, divides the topographic features of the peninsula 

 Sierra into three sections:^ 



(1) The coast range, rising gradually from the sea to an elevation of 

 3,000 feet in a distance of 20 to 30 miles. Surmounting this area several 

 minor ranges and sharp peaks attaining an elevation of 3,000 to 4,000 

 feet. A rapid descent leads from the divide of the coast range to — 



(2) The interior valleys, an interrupted series of depressions in the 

 middle of the chain at an elevation of 1,800 to 2,000 feet. 



(3) The eastern range, rising rapidly from the valleys and continuing 

 as an almost level plateau, with a gentle slope up to the peninsular 

 divide and an abrupt, almost precipitous, descent to the desert. The 

 elevation of this remarkable plateau is from 4,000 to 5,000 feet. 



"This plateau region, which supports a considerable growth of pine 

 forest, extends, according to the meager accounts obtainable, from the 

 boundary southward about to latitude 31°, reaching its culminating 

 point in the high mountain mass now known as San Pedro de Martis, 

 which is apparently the same as the snow-capped mountain called in 

 the Narragansett report " Oalamahue," or Santa Oatalina (Caterina) 

 Mountain. 



"The area examined by the present writers, which extends 15 to 30 min- 

 utes north and south of the thirtieth parallel of latitude, is separated by 

 a considerable gap of unknown country from that described by Lindgren. 

 In this latitude the average elevation of the peninsula is about 2,000 

 feet, and that of its higher ridges may be taken at less than 3,500 feet. 

 It is a singularly arid region, having practically no running water on 

 the surface and very few permanent springs; nevertheless our experi- 

 ence has shown that properly located wells obtain a fair supply of 

 water at depths of 20 to GO feet. The climate is remarkably equable 

 and healthful, being but little warmer than that of the coast region of 

 southern California, and as a rule much drier. The diurnal changes 

 of temperature are, however, very great. It is swept by continuous 

 breezes from either coast, which appear to blow alternately about three 

 days at a time, those from the Pacific being laden with more or less 

 moisture, while the east winds are extremely dry. Like California, it 

 has a rainy season in the spring, but this is generally but a few days' 

 duration and extremelj^ irregular and uncertain." 



I Notes on the Geology of Baja California, Mexico. Proc. Calif. Acad, of Science, 

 I, 1888, p. 170. Idem, II, 1889, p. 1. Idem, III, 1890, p. 26. 



