18 CALIFORNIA ACADEMY OF SCIENCES [Proc. 4th Ser. 



fornia Miocene, all contribute to the aggregate of variety that 

 is met with in the field and in the literature. 



While it will be admitted by all thoughtful geologists, — and 

 the idea is by no means new — that lithology can form no proper 

 basis for subdivision of the Miocene, still the thick group of 

 strata of this period, showing as it does the signs of wide- 

 spread disturbances, can not be considered as being over- 

 burdened by formational names when four or five have been 

 proposed. In the early stages of stratigraphic study, if it is 

 at all intensive, such names are necessary and should be wel- 

 comed when it seems necessary to the workers in the subject 

 to make them, and they should not be discarded without a 

 proper consideration, nor until shown by creditable authority 

 to be unnecessary. It may be frankly admitted by the advocates 

 of intensive stratigraphic study, without loss to their ideals, 

 that mistakes have been made in the early stages of their work, 

 but this fact should not discourage endeavor to find the order 

 that undoubtedly exists in their subject. The solution of the 

 problem, though not yet complete, is possible; and, if later 

 investigators have erred in their search for proper criteria of 

 differentiation, their endeavors have been toward advancement, 

 and their success, though partial, should be welcomed and 

 encouraged. Their errors, even if great, as they have not been, 

 are no greater than the errors of earlier writers, and if pointed 

 out, may still be amended. 



But the difficulties in the way of making a systematic study 

 and a systematic classification of strata should not of them- 

 selves discourage effort, nor can the difficulties inherent in the 

 language of science be properly urged as a reason for the rejec- 

 tion of its results. As an example of a regrettable attitude, a 

 recent writer has spent much effort to show that lithology can 

 not form a sound basis of classification, and it is asserted by 

 him that this has usually been the basis among previous writers. 

 This author then proceeds to discourage attempts at subdi- 

 vision, and endeavors to defend excathedra statements and con- 

 clusions that were on the face of them premature, and made 

 before all the facts were known. 



It has long been known that organic siliceous shales, such as 

 occur near the town of Monterey, are a "depositional facies" 

 that perhaps belongs to deep-water areas, and that strata of 



