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University of California Publications in Geology [Vol. 7 



few years the array becomes confusing and rather discouraging 

 to one who wishes to acquaint himself with the real essentials of 

 the geological history of that time. 



Salinas Valley, Hamlin, 1904. — It was Homer Hamlin who 

 suggested the term "Vaquero sandstone" for the sandy lower 

 portions of the Monterey series in the Salinas Valley region. 

 In 1904 in a paper on the Water Resources of the Salinas Valley, 

 California, 41 he defines it as follows: "Vaquero sandstone. — 

 In the Salinas Valley, the Vaquero sandstone is a well defined 

 formation. So far as observed in this region it rests uncon- 

 formable - on the Basement complex and on stratified terranes 

 older than the Neocene, being thus in this locality the oldest 

 known member of the Neocene; in other localities Neocene for- 

 mations are found below the Vaquero sandstones, indicating that 

 it is not the basal member of the Neocene. 



"'The Vaquero formation is a rather coarse, uniformly gray, 

 white or light-yellow quartzose sandstone with an occasional 

 .stratum of granitic pebbles. It is of great thickness along the 

 eastern slope of the Santa Lucia range, especially in Los Vaqueros 

 Valley ; hence the designation proposed by the writer for this 

 series of sandstones. . . . The following fossils have been found 

 in the Vaquero sandstone: Balanus, sp. ?; Mytilus, sp., probably 

 matheiosonii Gabb; Ostrea tayloriana Gabb (Young)?; Ostrea 

 titan Conrad?; Pecten magnolia Conrad; Turritella hoffmanni 

 Gabb?; Chione matkewsonii Gabb; Chione n. sp. (large, charac- 

 teristic of this horizon) ; Mactra aff. catilUformis Conrad; Pecten 

 estrellauus Conrad; Pecten (Chlamys) n. sp., S. ; Pecten (Pla- 

 gioctenium) n. sp. A." 



San Luis Quadrangle, Fairbanks, 1901. — Fairbanks adopted 

 Hamlin's nomenclature for the San Luis Folio, which was pub- 

 lished (appearing in fact earlier) the same year. He places in 

 the "Vaquero Sandstone" that lower portion of the series which 

 is made up of sandstone and conglomerate "because of their 

 extensive occurrence on Los Vaqueros Creek. ' ' Beyond the quad- 

 rangle it reaches a great thickness, especially "along the southern 

 side of the granitic area." It may be 5000 to 6000 feet thick. 



« U. S. Geol. Surv.. W. S. and Irrig. Paper no. 89. 



