AKNOLD— THE PALEONTOLOGY AND STEATIGEAPHY OF SAN PEDKO. 



21 



Dr. Lawson in discussing the movements that have taken place during late 

 Tertiary and Pleistocene times in the vicinity of San Pedro, says :' "It follows that, 

 while there is a very profound physical break between the Miocene and Pliocene, 

 the marine Pliocene and Pleistocene formations are intimately associated, with no 

 epoch of subaerial denudation between them." The observations of the writer also 

 show this to be true, although in some places there is evidence of local denudation 

 between the Pliocene and Pleistocene. At Deadraan Island, in particular, there is 

 evidence of a period of denudation between the two. 



Beds of a fine gray sand, with gentle north dip, rest upon the Pliocene ex- 

 posed along the railroad grade leading up to the cut in the bluff in the southeastern 

 portion of San Pedro. (See diagram D, PI. XXII.) The exact relation between 

 these gray sands and the underlying Pliocene is uncertain, as detritus covers the con- 

 tact along the face of the bluff. But the gray sand beds seem to rest almost conform- 

 ably on the yellow Pliocene deposits, both having a low dip toward the north. One 

 of the layers of gray sand near the top of the bluff north of the railroad grade con- 

 tains a fauna similar to that of the lower San Pedro stratum of Deadman Island. 

 This stratum is exposed in the bluff to the north of the San Pedro valley, and also in 

 two small cuts in the bluff west of the business portion of the town. These gray 

 sand strata were continuous at one time, the San Pedro valley, which cuts them, 

 having been formed by recent erosion. 



In the bluff to the north of the valley the fossiliferous lower San Pedro stratum 

 is about forty feet above tide level and dips northward, disappearing under detritus 

 at the mouth of a small ravine about three hundred yards from the southern end of 

 the bluff, but aj^pearing again north of the ravine at the base of the bluff. Under- 

 lying this lower San Pedro bed are gray sandy strata which correspond to the lower 

 part of this same formation soutii of the valley, and which are unfossiliferous, except 

 in a few places. The following fossils have been found in the lower San Pedro beds 

 in the San Pedro bluffs. 



List of Fossils of the Lower San Pedro Beds at the San Pedro Bluffs. 



Angulus buttoni 

 Anomia lampe 

 Cardium corbis 

 Corbula luteola 

 Cryptomya calij'oi-nka 

 Cumingia caUfornica 

 Donax caUfornica 

 Donax Icevigala 

 Hinnites giganteus 

 Kellia laperousii 

 Kellia suborbicularls 

 Lievicardium substriatum 

 Lazaria subquadrata 



PELECYPODA. 



Leda var. prcecursor 

 Leda laphria 

 Lucina acutiUneata 

 Lucina caUfornica 

 Lucina nutlaUi 

 Lyonsia caUfornica 

 Macoma nasuia 

 Macoma secta 

 Macoma yoldiformis 

 Maclra falcata 

 MyliUmcria nuttalli 

 N^ucula castrensis 



Nucula suprastriata 

 Oslrea lurida 

 Pecten latiauritus 

 Peclen \av. monotimerv 

 Psephis salmonea 

 Psi'phis iantilla 

 Scmele decina 

 Siliqua lucida 

 Solen rosaceus 

 Solen sicarius 

 Tapes staminea 

 TelUna bodegensis 



1 Poat-Pliocene Diastrophism of the Coast of Southern California. By A. C. Lawson. Bull. Dept. Geol., Univ. of California 

 Vol. 1, 1893, p. 128. 



