NOTES ON THE MESOZOIC AND CENOZOIC PALEON

TOLOGY OF CALIFORNIA.

BY CHARLES A. WHITE.

GENERAL REMARKS.

Having been for a number of years engaged in the study of those Mesozoic and Cenozoic formations of the United States which lie between the one hundredth and one hundred and fourteenth meridians, it became desirable that I should make some comparisons of them with the formations of similar age which are known to constitute important portions of the geological series as it is developed in the Pacific coast region. Dr. G. F. Becker, in charge of the Pacific division of the Survey, in the course of his investigations also found it necessary to the proper elucidation of certain of the problems involved in his work that some special paleontological studies should be made in connection with it. I therefore, by request of the Director, devoted the season of 1884 to such investigations as have a direct bearing upon the Mesozoic and Cenozoic formations of California, extending my field observations to numerous localities within that State and to certain localities in Oregon also. These investigations were pursued in association with Dr. Becker, who gave his attention to the more purely geological questions with which they are intimately connected. The results of our respective studies are published in companion bulletins of the Survey, Nos. 15, (the present one,) and 19.

While only a few months have been given especially to this work upon the Pacific coast, I have had the advantage of a previous acquaintance with the results of the labors of all other authors who have written upon the paleontology of California; and these advantages I deem sufficient warrant for the conclusions which I have reached, and for their publication in the present form. Upon undertaking this work the questions which seemed more especially to demand my attention were, first, the true geological age of the Téjon Group of the California geologists, and its relation to such of the associated groups as they had also recognized, that is, the relation of that group to the Miocene above and to the Chico and Shasta Groups beneath; second, the relation between the Chico and the Shasta Groups; third, the relation of the Shasta Group to the other

Cretaceous formations, and to the so-called Auriferous Slates of California.

One of the principal obstacles to the satisfactory accomplishment of this work has been found in the fact that the fossil faunas of the Pacific coast region differ so greatly from those which are presumably of the same age respectively in other parts of the continent. Indeed, a conspicuous feature of the paleontology of that western region, at least as regards the formations from the Shasta, to the Téjon Group, inclusive, is the great paucity, and perhaps the entire absence, of fossil species in those formations respectively which are identical with any that are found in formations presumably of the same age which lie to the eastward of that region. Similar remarks will also apply to the Miocene and later deposits of the Pacific coast. Furthermore, the Carboniferous fauna of that region, so far as it is known, presents marked differences from that of any of the divisions of the Carboniferous series as it is known in other parts of North America. Therefore, in the paleontological study of the Pacifi coast formations one must discuss their respective equivalent formations in other parts of the continent and in other parts of the world mainly with reference to the generic and family types which are represented in their respective faunas. This dissimilarity between the fossil faunas of corresponding formations of the Pacific coast region and of the central and eastern portions of this continent is quite as great as it is between corresponding formations in Eastern North America and Europe. In many cases, indeed, one may discuss questions concerning the equivalencies of formations in Eastern North America and Europe, respectively, with more confidence than similar questions concerning the formations of eastern and western portions of North America.

In discussing the paleontological questions here proposed I shall have frequent occasion to refer to geological structure; and it will be necessary for me to use in this connection the classification of strata which was proposed by the State geological survey of California for that region, and which has become generally accepted by geologists. A portion of that classification, however, was not regarded by the geologists of the California survey as fully established, and it was proposed by them only provisionally. It is proper for me to say in this connection that not only do these provisional portions of that classification still remain unsettled, but that I also find the limits, both faunal and stratigraphical, of a part of the formations which they fully recognized to be indefinite and of doubtful character.

My season's field work upon these formations has been in a good de

'Some Chico fossils have, however, been found to the eastward of the Cascade Mountains, in Oregon; but the extent of the formation which contains them there, and its relation to the Cretaceous strata further eastward, is not known. See remarks on subsequent pages concerning the identification of California fossils with Eastern species; also remarks on the separation of contemporaneous Cretaceous faunas.

gree satisfactory, because I was able to collect in person many of the species of fossils which characterize the respective groups of strata, and because I was able to verify numerous unpublished observations previously made by Dr. Becker, besides many others which were made still earlier by Prof. J. D. Whitney, the results of which are published in the State Geological Reports of California.2 In fact I have verified so many of the published observations of Professor Whitney that I do not hesitate to accept his statements in such other cases as I shall find it necessary to refer to in the following discussions.

I find the case somewhat different, however, as regards the work done by Mr. W. M. Gabb in connection with the geological survey of California; but the adverse views which I have formed in relation to it refer much more to the conclusions which he reached than to the published details of his observations and of his descriptive paleontology.3 Taking up the subjects which it is proposed to discuss in this article, in the order in which they are mentioned in a previous paragraph, we have first to consider the Téjon Group. In his studies of the Mesozoic and Cenozoic formations of California, Mr. Gabb recognized four groups of strata as referable to the Cretaceous period; and this classification was officially adopted by the geological survey of that State. As one looks through the published writings of Mr. Gabb in relation to the grouping of the California strata, and their age and relations to the recognized groups of North America and Europe, a certain want of harmony appears in regard to the statements which he has made. I think it is only just to say that I regard this as largely due to the modification which his views necessarily underwent during the progress of his work, although he appears not to have made any explicit statements to that effect in any of his later publications. I shall therefore refer more especially to his later utterances, as I find them in the various publications to which he has contributed, especially in Vol. II, Paleontology of California, omitting as far as practicable material reference to his earlier views, although many of the discussions which have arisen in relation to them refer to the latter.

The following paragraphs, copied from Professor Whitney's preface to Vol. II, Paleontology of California, pp. xiii and xiv, give a concise account of those formations in accordance with Mr. Gabb's later views and as they were finally adopted by the State survey. It is these formations alone that I propose to discuss in this article, and I shall consider the other formations of that region only in their relation to these. 1. The Téjon Group, the most modern member, the Division B of Paleontology, Vol. i, is peculiar to California. It is found most extensively developed in the vicinity of 'See Vols. I and II, Paleontology, and Vol. I, Geology of California.

3 Mr. Gabb's work on the fossils of California is mainly contained in Vols. I and II of the Paleontology of California, but the following papers may be referred to for other discussions which relate to his work in that State: American Journal of Conchology, II, pp. 87-92; V, pp. 5-18; American Journal of Science, (2), XLIV, pp. 226– 229; Proceedings of the California Academy of Science, III, pp. 301-306; V, pp. 7–8.

Eort Téjon and about Martinez. From the latter locality it forms an almost continuous belt in the Coast Ranges to Marsh's, 15 miles east of Monte Diablo, where it sinks under the San Joaquin Plain. It was also discovered by different members of the survey at various points on the eastern face of the same range as far south as New Idria, and in the summer of 1866, by Mr. Gabb, in Mendocino County, near Round Valley, the latter locality being the most northern point at which it is yet known. It is the only coal-producing formation in California.

This group contains a large and highly characteristic series of fossils, the larger part peculiar to itself, while a considerable percentage is found to extend down into the next group, and several species still further down into the Chico Group. Mr. Gabb considers it as the probable equivalent of the Maestricht beds of Europe.

2. The Martinez Group is proposed provisionally, to include a series of beds, of small geographical extent, found at Martinez and on the northern flank of Monte Diablo. It may eventually prove to be worthy of ranking only as a subdivision of the Chico Group.

3. The Chico Group is one of the most extensive and important members of the Pacific coast Cretaceous. Its exact relations with the formation in Europe have not been fully determined, though it is on the horizon of either the Upper or Lower Chalk and may prove to be the equivalent of both. It is extensively represented in Shasta and Butte Counties and in the foot-hills of the Sierra Nevada as far south as Folsom, occurring also on the eastern face of the Coast Ranges bordering the Sacramento Valley, at Martinez, and again in Oristimba Cañon, in Stanislaus County. It includes all the known Cretaceous of Oregon and of the extreme northern portion of California, and is the coal-bearing formation of Vancouver's Island.

4. The Shasta Group is a provisional name, proposed to include a series of beds of different ages, but which, from our imperfect knowledge of the subject, cannot be separated; it includes all below the Chico Group. It contains fossils, seemingly representing ages from the Gault to the Neocomian, inclusive, and is found principally in the mountains west and northwest of the Sacramento Valley. Two or three of its characteristic fossils have been found in the vicinity of Monte Diablo, and one of the same species has been sent from Washington Territory, east of Puget Sound. Few or none of its fossils are known to extend upwards into the Chico Group.

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THE CHICO-TEJON SERIES.

It appears from Mr. Gabb's later publications that he recognized that all the strata from the base of the Chico Group to the top of the Téjon form an unbroken portion of the great geological series. And yet, with perhaps the exception of his Martinez division, which he proposed provisionally, he always discussed those divisions as if they were as distinctly definable as geological formations usually are. Geologists will probably always find it convenient to retain the names Téjon and Chico for the upper and lower portions of this series, respectively, but I have not been able to find any good reason for retaining the name Martinez Group for any portion of it. I shall therefore reject the Martinez Group so far as my own discussions of the series here referred to are concerned. The first published fossils of that series of strata which afterward received from the California survey the name of Téjon Group were obtained by parties of the Pacific Railroad surveys, some thirty years ago. These fossils were described by Mr. T. A. Conrad in the reports of that survey, and by him referred to the Eocene Tertiary. So far as I am aware, he never changed his mind as to the geological age of these fossils, nor of the group of strata from which they and many others were afterward obtained. On the contrary, he repeated the publication of his views and strongly contended for their accuracy. Mr. Gabb alone, so far as I am aware, has published any of the fossils of the Téjon Group as of Cretaceous age; and this be did with a positiveness of assertion which, while it left no doubt as to his views, is only warranted in cases where the evidence is abundant and unquestionable from any reasonable standpoint.

The publication of Mr. Gabb's views with the sanction and in the reports of the geological survey of California gave the matter so much the air of authority, that various authors accepted those views as to the Cretaceous age of the Téjon Group, and for several years after Conrad's death it was not seriously called in question.

Professor Dana, however, has practically called those views in question, suggesting that the Téjon Group is of Eocene age, and probably equivalent with the Laramie Group.

*See Pacific Railroad Reports, Vol. V, pp. 317–329.

See Amer. Jour. Sci., (2), XLIV, pp. 376--377; Amer. Jour. Conch., I, pp. 362-365; II, pp. 97-100; Smithsonian Check-List of Eocene Fossils.

"See especially Proc. California Acad. Sci., III, p. 301.

7See Dana's Manual of Geology (1876), p. 491.