236 Adventures in Scenery 



here. Areas of basalt are widely distributed. They are rem- 

 nants of lava flows which are thought to have extended over a 

 large part of the region previous to the uplift of the mountain 

 range. Erosion has dissected the basalt beds so that they occur 

 now only in patches. 



Glaciation has played a part in fashioning the surface in the 

 highest parts of the range. At first thought it may seem sur- 

 prising that glaciation should occur in this southern latitude. 

 However, San Gorgonio Mountain and the ridge extending 

 westward show unmistakable evidence of the effects of glacial 

 ice. In Quaternary time (the era in which the Glacial Period 

 occurred) the climate may have been colder than at present. 

 The fact is, however, that today a little snow lingers on the 

 higher slopes throughout the year. 



Evidences of Glaciation on Ridge 



West of San Gorgonio Mountain 



On the north side of the high ridge that extends westward 

 from San Gorgonio Mountain between Santa Ana River and 

 Mill Creek well defined glacial cirques and moraines occur, giv- 

 ing certain evidence of glacial ice action. There is a typical 

 glacial cirque on the northeast side of San Gorgonio Mountain. 

 Less than a quarter of a mile below a well developed moraine 

 lies across the uppermost part of the north fork of Whitewater 

 River. On the northwest side of San Gorgonio Mountain a 

 large moraine lies across the east branch of the south fork of 

 Santa Ana River. A most ideal example of a glacial moraine 

 is at the head of Hathaway Creek, northwest of San Gorgonio 

 Mountain. A long narrow tongue of ice reached down the 

 valley a mile and left a nearly perfect moraine. Five semicir- 

 cular terminal moraines cross the canyon. The middle one is 

 formed of immense blocks of rock, which when viewed from 

 below its curving front forms a wall nearly 100 feet high. 

 Conditions in the region indicate that glaciation was of con- 

 siderable duration. 



