4(30 



University of California. 



[Vol. 3. 



rienced here within the historical period. There is no collateral 

 evidence of a period of severe earthquakes in the latter portion 

 of the Quaternary Era, and, besides, I doubt the efficiency of 

 a series of earthquakes to produce the phenomena observed. 



3. The hypothesis which I accept is that the landslides con- 

 nected with the 120-foot terrace are due to the same abnormal 

 climatic condition as produced the torrent fans. This condition 

 was one of excessive rainfall. Cloud-bursts with prevailing semi- 

 arid conditions would not soak the earth to a sufficient depth 

 to cause such a general landsliding. It required long, heavy rains. 

 This season has been one of abnormal precipitation. From the 

 3rd of February to the 29th of March there was almost contin- 

 uous storm, and about forty inches of rain fell in Orleans. Many 

 of the smaller landslides settled several feet, but no large ones 

 were formed, and no torrent fans similar to those of the 120-foot 

 terrace. The torrent-fan and landslide-forming period must 

 have been one of almost continuous heavy rain for months, with 

 frequent cloud-bursts. It was almost of a cataelysmal nature — 

 a sort of incipient "Deluge." I am a firm believer in the 

 usually mild processes of Nature, but we certainly have evidence 

 here of something abnormal. 



During this period of excessive precipitation, the river occu- 

 pied the lower channel under the 120-foot terrace. The gravels 

 of this channel are markedly coarser and thicker than those of 

 preceding channel. This is due largely to the coarse debris thrown 

 into the channel by the landslides and coarser torrent fans. 

 The river must have been greatly increased in volume, other- 

 wise the sudden influx of this coarse material would have caused 

 its channel to be aggraded much more than it was. Thus the 

 conditions of the channel furnish corroborative evidence of 

 excessive rainfall. 



This siipposed period of excessive humidity appears to have 

 immediately succeeded the maximum extension of the glaciers 

 of the so-called Intermedite Stage. It is probable that the warm 

 rains caused the glaciers to be rapidly melted away. If I am 

 correct in correlating these ' ' Intermediate ' ' glacial deposits with 

 the Iowan drift of the Eastern States, it will appear that the 

 period of excessive rainfall in the Orleans Basin was identical 



