Geology from a Motor Car 335 



Not all the scenic routes in California are described in the 

 2,638 miles covered by these tours. To adequately describe all 

 would require a large volume. Geologic facts of interest are 

 pointed out on some important highways for the benefit of 

 those who wish to see what they look at as they go. Do not 

 be in a hurry. To travel from one place to another is one thing. 

 To really see and enjoy the landscape is another. Speeding at 

 60 or 70 miles an hour, with stops only for gasoline, may be 

 "travel"; it is not seeing the country. There are those who 

 travel for the sole purpose of getting to some other place (gen- 

 erally in a hurry) . Others enjoy what they see as they go. 

 The following pages are for the latter class. 



There is no particular reason why these "tours" should begin 

 at San Diego. It was from there that the author made his first 

 auto tour "seeing California," and this remains in his mind as a 

 "gem" tour. But any trip anywhere in California may be a 

 "gem tour" if only one "has eyes to see," and is not in too 

 :much of a hurry. 



ROUTE A. SAN DIEGO, VIA SALTON SEA AND PALM 

 SPRINGS TO Los ANGELES. 390 MILES 



The San Diego Coastal Plain 



San Diego to El Centre, 123 miles. The route lies across 

 the Peninsular Range of mountains. (See Chap. XVII.) The 

 city is about 50 feet above sea level. In Quaternary time, geo- 

 logically yesterday, the land was about 200 feet higher than 

 now. Rivers entering the ocean cut deep valleys. Later the 

 land sank about 100 feet lower than now, and the river mouths 

 were "drowned." San Diego Bay is cut off from the ocean by 

 the filling of sediments carried down by the streams and which 

 liave not been carried away since the land was elevated to its 

 present height. Mission Bay, north of the city, is the drowned 

 mouth of San Diego River. Rising above the city to the east 

 .are mesas or terraces and wave-cut cliffs 75 to 100 feet above 

 :sea level, cut by the waves when the land was 100 feet lower 



