15 



and shoreline bjuffs ^ormed at a higher stand of sea level. 

 The material composing these old sand bars is a fine brown 

 thin-bedded sand that has been washed free of all clay 

 material , 



Ballona Gap 



Ballona Gap is a terrestrial feature of importance in the 



study of Santa Monica Bay as large amounts of sediment have 

 been carried through it to the shelf and offshore region. 

 Drainage through the gap has probably played an important 

 role in the history of Santa Monica submarine canyon and per- 

 haps, to a minor extent, Redondo Canyon. Ballona Gap at its 

 narrowest place is 1.2 miles wide where it cuts through the 

 Inglewood -Newport fault zone, and is about 10 miles long in 

 its present extent from the coast to the east end of Baldwin 

 Hills. Bluffs up to 400 feet high were cut by the old stream 

 as it flowed between Baldwin Hills and Beverly Hills. There 

 is evidence that an antecedent stream existed on the surface 

 of Late Pleistocene (Palos Verdes) age before it was deformed. 

 The stream had sufficient eroding power to cut across the warped 

 rocks as quickly as they were uplifted. 



The ancestral Los Angeles River which formed the Ballona 

 Gap cut a channel at least 50 feet below sea level at Ballona 

 Creek outlet, and 400 feet deep where it crossed Baldwin Hills. 

 Subsequent deposition of gravels and sands has filled the channel 

 at the coast and to a depth of 80 feet northeast of Baldwin 

 Hills (9 miles upstream). According to Poland, et^ al^. , (1948, 

 p. 51), the incised stream graded to base level substantially 



