EXPLORING one of the larger pools on Rancho 

 La Brea in his first boat, built about 1890, Cap- 

 tain Hancock and his younger brother find the 

 surface water shallow and the tarry depths 

 treacherous. 



VISCOUS ASPHALTUM pool which has been 

 drained of water is shown below as it appears 

 today — gas pressure from subterranean depths 

 forming iridescent globules on the surface, 

 which break and recede slowly in ever-widen- 

 ing concentric circles. 



^m '^HIb 



il 



