GABB'S DIVISIONS. 179 



The follo\ying' paragi-aphs, copied from Professor Whitney's preface to 

 Geol. Survey California, Paheoutology, vol. 2, pages xiii and xiv, give a 

 concise account of these formations in accordance with Mr. Gabb's later 

 views and as they were finally adopted by the State survey: 



(1) TheTejoa group, the most nioileru member, the Divisioa B of Paleoutolog^y, 

 Vol. I, is peculiar to Oaliforuia. It is fouiiel most exteusivoly developed in the vicinity 

 of Fort Tcjou aud about Martinez. From the latter locality it forms an almost con 

 tinuous belt in the Coast Ranges to Marsh's, 15 miles east of Monte Diablo, where it 

 sinks luider the Sau Joaquin plain. It was also discovered by the difiereut members of 

 the survey at various points on the eastern face of the same range as far south as New 

 Idria, and, iu the summer of ISGG, by Mr. Gabb, in Mendocino County, near Round 

 Valley, the latter locality being the most northern point at which it is as yet known. 

 It is the only coal-produciug 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 extending below into 

 the next group, and several species still further down into the Cliico group. Mr. 

 Gabb considers it as the probable equivalent of the Maestricht beds of Europe. 



(2) The Martinez group is propo.sed 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 aud important members of the 

 Pacific Coast Cretaceous. Its exact relations with the formation in Europe have not yet 

 been fully determined, though it is on the horizon of either the Upper or Lower Chalk, 

 and may probably prove to be the equivalent of both. It is extensively represented 

 iu Shasta and Butte Counties and in the foot-hills of the Sierra Nevada as far soutli a.s 

 Folsom, occurring also on the eastern face of the Coast Ranges bordering the Sacra- 

 mento Valley at Martinez, aud again in Oristimba Cailon, in Stanislaus County. It 

 includes all of the known Cretaceous of Oregon and of the extreme northern portion 

 of California, and is the coal-bearing formation of Vancouver's Island. 



(■L) Tiie Sh ista 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 yet 

 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 aud 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 Paget Sound. Few 

 or none of its fossils are known to extend upwards into the Chico group.' 



To these I have added another sei-ies of Cretaceous strata lying above 

 the Shasta, and, according' to the paleontological evidence, below the 



'Mr. Gabb's work on the fossils of California is mainly contained in Geol. Survey California, Pa- 

 litoDtology, vols. 1 and 2; but tlie following papers maybe referred to for other discussions which relate to 

 his work in tliat State: Am. Jour. Conchol., vol. 2, pp. 87-92; ibid., vol. 5, pp. 5-18; Am. Jonr. Sei.,2d 

 series, vol. 44, 18(i7, pj). 2:}fi-339 ; Proc. California Acad. Nat. Sci., vol. 3, pp. 301-306; ibid., vol. 5, pp. 7-8. 



