1922] Vaughan: Geology of San Bernardino Mountains 389 



that it bears out a previous statement that aridity prevailed during 

 this period. The same conditions existed in Mill Creek Carion, but 

 all that remains of the fanglomerate at present are some low hills and 

 a terrace. On the north side of the canon at Akers Camp there is a 

 fanglomerate bench which is no doubt a remnant of the old valley 

 floor. A similar occurrence is found at the mouth of Potato Canon. 



Fanglomerate forms the main valley floors around the headwaters 

 of Whitewater River, and Raywood Flat is a remnant of just such an 

 old floor. This consists of unsorted angular and subangular fragments 

 of granite and schist from the neighboring ridges. In some places it 

 shows a rude stratification with lenses of sand free from pebbles. 

 These lenses, hoAvever, are usually small, only five to ten feet in length. 

 The gravel consists of small rock fragments with muscovite, biotite, 

 and even feldspar, as well as quartz. Near the head of the north fork 

 of Whitewater the fanglomerate is over 200 feet thick. At first sight 

 it appears to be entirely without stratification, but viewed from a few 

 hundred feet distant a rude horizonal bedding can be recognized. One 

 subangular boulder was seen which was about 20 feet across in its 

 greatest dimension and others 10 feet in diameter are not uncommon. 

 This material, being at such an altitude, might be taken for glacial 

 debris ; especially owing to the presence of huge boulders. But there 

 are some things to be noted which rule out this possibility altogether. 

 Most of the deposit, even the coarse material, exhibits a rude bedding. 

 When the whole mass is viewed from a vantage point it is seen to 

 form large even-graded areas filling in old depressions and grading 

 harmoniously into the surrounding hills. There is true glaciation on 

 the north side of this same ridge, but the moraines do not extend so 

 low as this detritus on the south side by fully 2000 feet. Yet the limit 

 of glaciation must be lower on the north side where glaciers would 

 have been more protected from the heat of the sun. The lithologic 

 similarity of the mass to the fanglomerate in Santa Ana Canon and 

 in Mill Creek is very striking, and this alone is sufficient to suggest a 

 similarity in origin. 



At the upper end of Mission Creek, just below the divide, .are 

 remnants of fanglomerate having the same relation to the surrounding 

 topography as that in the Santa Ana Canon and like it consisting 

 largely of angular boulders. 



Just below Pine Bench is a fanglomerate which, because of its 

 elevation and location (see map), looks as though it were once contin- 

 uous with Banning Heights and simply separated by erosion. This 

 is more apparent in the field when looking southward from Pine 



