178 GUIDEBOOK OF THE WESTERN UNITED STATES. 
exhibited in an attractive and instructive manner. The museum 
authorities control the wonderful bone deposits in the asphalt springs 
of Rancho La Brea, about 8 miles directly west of the city. These 
springs have been for centuries the most effective natural animal 
trap known, and the asphalt has preserved the bones of the thousands 
of extinct as well as modern animals caught in its deceptive and 
sticky pools. The skeletons of elephants, camels, sloths, saber-— 
toothed tigers, bears, and myriads of smaller animals, including many 
birds, are being gradually dug out and set up in the museum. Among 
the bones has recently been found the skull of a human being who 
lived probably ‘not less than 10,000 years ago, contemporaneously 
with many animals now extinct. 
- With the permission of the Museum of History, Science, and Art 
the Rancho La Brea may be visited. On the way thither the traveler 
passes over a portion of the great alluvial plain of Los Angeles, which 
is underlain, at least in part, by three Quaternary formations, the 
oldest of which is a marine deposit laid down horizontally on the 
beveled edges of a very thick series of tilted Pliocene beds. This 
marine Quaternary deposit has a thickness of 100 feet in the north- 
western portion of the city, but thins to an edge near the ancient sea 
cliff beyond. Los Angeles River excavated a valley about a mile 
wide and 100 feet deep in the marine deposit and filled the trench 
with river deposits, the second Quaternary formation. This in turn 
is covered by the alluvium of the present plain. 
