350 The American Geologist. June, 1902. 
of the fascinating subject of the Pacific coast Cenozoic geol- 
ogy brings us nearer to the final elucidation of its problems. 
The southern California field is unique in that the forma- 
tions are so well exposed. Much of the country is virtually 
a desert and although life conditions in it are somewhat 
strenuous, the enthusiastic geologist will willingly overlook 
a few hardships for the sake of having the structure as clear- 
ly displayed in a distant view as though charted. One may 
stand on a peak overlooking some of the Pliocene basins and 
determine the structure of many square miles of territory and 
thousands of feet in thickness of strata almost as readily as if 
he held the basin in his hand and took it apart block from 
block. 
In the valley of the Santa Clara river of the South, about 
30 miles north of Los Angeles, there is a basin-shaped depres- 
sion in the older rocks occupied by Upper Pliocene strata, 
and at its extreme eastern end there appear remnants of older 
Tertiary formations which will be discussed 1nder the names, 
respectively, of the Escondido and Mellenia series. 
THE Esconpipo SERIES 
Near the head of Tick Canyon, about four miles north of 
Lang station on the Southern Pacific railway in Los Angeles 
county, the following section from north to south and begin- 
ning at the bottom of the series, was roughly measired along 
the sides of a gorge where there is a beautiful exposure: 
Type-section of the Escondido series in Tick canyen. 
Gneiss (older complex) occupies first 5,000 feet of canon. 
Thickness. 
Basal conglomerate, Diuitse verticaler- np ss.. cecum 780 feet. 
Coarse buff and light ereem sandstone \... 3-!:.. sn cae 70 feet. 
3. White sandstone, alternating with a white thin bedded 
or banded material apparently either a rhyolyte with 
Low. Strictube on shiv Olyte cutee erst ere errr ote 230 feet. 
. 
load 
to 
4. Dark red and brown lava of basic composition, showing 
flow structure; semi-crystalline. Some layers are por- 
phyritic and some slightly amygdaloidal. Much of it is 
stained bright green. It appears too basic for andesyte 
and 1s. probably (a. basalt’ was oceeds 06 o> 2 + POORER 
5) sbright light red sandstone and™=shale,).....--.ssseeee go feet. 
6 Dark brown’ basalts Ge) avers acc noes bares See eee GnGeEE 
Rede isamdStOme; 1. cuscne.e inayat ace Meee nePeke tarenese, Sess ee archon 
cos 
Green’ ssamd'stome: — sen occas Sake ene ae Cae ace eer ep one 10 feet. 
