Vol. IX] SMITH— CLIMATIC RELATIONS 13 



pared with the present. This epoch probably corresponds to 

 the time of maximum glaciation of the continent. R. A. Daly^ 

 has estimated that the general lowering of temperature at the 

 maximum glaciation was about 14° F., which agrees with the 

 figure given. 



Upper San Pedro. This fauna is best known at San Pedro, 

 Dead Man Island, and Santa Barbara; the beds in which it 

 occurs lie unconformably above the lower San Pedro, and con- 

 sist of unconsolidated sands, gently tilted. The time interval 

 between the two formations is not long, but long enough for the 

 climate to have changed entirely, for the temperature to have 

 risen from 12° F. below the present to about 4° F. above the 

 present; long enough for the isotherm of 50° F. to have been 

 pushed far to the north, and for that of about 66° F. to have 

 invaded southern California. Among the important species of 

 the upper San Pedro are: Amiantis callosa Con., Cardium ela- 

 tum Sby., Chione succincta Val., Metis alta Con., Pecten cequi- 

 sulcafus Carp., Pitaria neivcomhiana Dall, Astrcea iindosa 

 Wood, Chorus belcheri Hds., Gyrineum californicum Hds., 

 Siphonalia kellettii Hds., (all Recent species in southern Cali- 

 fornia) ; and Cardium procerum Sby., Chione gnidia Sby,, 

 Chione neglecta Sby., Dosinia ponderosa Gray, Miltha chil- 

 dreni Gray, Mactra exoleta Gray, Mulinia grayi Dall, Pecten 

 dentatus Sby., Pecten subnodosus Sby., Eupleura murici- 

 formis Brod., Macron kellettii Hds., Nassa versicolor Adams, 

 Mellita longiiissa Mich, (all tropical species in Lower Cali- 

 fornia or the Gulf of California) ; and Cancellaria tritonidea 

 Gabb, Crepidula princeps Con. and Pisania fortis Carp., which 

 are extinct. 



The upper San Pedro is not post-Glacial, the number of ex- 

 tinct mollusca, about five per cent in a large fauna, being too 

 great for that to be possible. It is probably interglacial. There 

 was in Europe, after the second glaciation, a warm epoch in 

 which the temperature of southern Europe was higher than 

 that of the present. It may be that the upper San Pedro epoch 

 corresponds to this. The cause of the rise was not local. 



We have no way of measuring the time that has elapsed 

 since the upper San Pedro, but it was long enough for about 



'Glacial control theory of coral reefs. <Proc. Ainer. Acad. Arts and Sci. Vol. 51, 

 No. 4, (1915) p. 168. 



