352 CALIFORNIA ACADEMY OF SCIENCES. 



the strata are suggestive of marine origin, strengthening 

 the evidence presented above of a very recent submerg- 

 ence. Dr. Lawson ascribes to these upper beds a PHo- 

 cene age.* 



As some question has been raised as to whether these 

 terraces are not the result of erosion rather than of sedi- 

 mentation, it may be well to call attention to the evidence 

 more in detail. In the first place, these terraces and 

 fillings show only horizontal bedding; further, the bed- 

 bing of the strata forming the hillsides is in nearly, if not 

 quite, every case where found, more or less highly in- 

 clined, and finally, in nearly every ravine one or more 

 contacts were found where the horizontal strata can be 

 clearly seen lying upon the highly inclined strata of the 

 Merced series. A few of these might be mentioned. 

 The formation at the head of Wood's Gulch has already 

 been described. In the ravine which heads up against 

 Wood's Gulch, a few yards below the Old San Pedro- 

 Colma road, the Merced sandstones and thin bedded 

 gravels are well exposed, having an almost perpendicular 

 dip. On the edges of these perpendicular beds lie the 

 horizontal Quaternary strata. These horizontal strata 

 may be traced continuously down the ravine to where 

 they contain quite a number of horizontal pines near the 

 crossing of the New San Pedro-Colma road. In a branch 

 of this same ravine occurs a recent cutting from fifty to 

 seventy-five feet deep. The inclined stratification of the 

 lower beds was not seen in the cut, but was found only a 

 hundred or two feet away. 



In the cut just north of the Happy Valley House the 

 horizontal Quaternary overlies strata of the Merced series 

 having a dip of 35° N, 20" E. 



Dr. Lawson has pointed out that the whole coast has 



* Univ. of Gal., Bull. Dept. GeoL, vol. i, p. 146. 



