194 University of California Publications in Geology | Vol. 7 



"Monterey" Avas first definitely given and defined. It is a his- 

 torically interesting paper in that it is the first notice of that 

 type of deposit that is so widespread and important, both geolog- 

 ically and economically, in California — the siliceous, chiefly dia- 

 tomaceous. earths and shales. A careful reading, however, shows 

 no intention to either name or define any stratigraphic unit, — 

 the whole purpose was to announce the occurrence in thick de- 

 posit of this remarkable type of strata. A partial section is 

 given, the lowest member of which was not estimated as "it 

 extends downward under the chamisal for a long distance." 



"This interesting formation, teeming with the skeletons of 

 microscopic organisms, appears to overlie and to be conformable 

 with the tertiary strata that underlie a part of the town of 

 Monterey and extend to and beyond the Mission of San Carlos. 

 These strata rest upon a porphyritic granite" (p. 330). These 

 latter strata are said to contain fossil shells, the more abundant 

 of which Conrad described and named Tellina congesta, which 

 at San Carlos is associated with Lutraria Traskii, also a new 

 species. 



"A stratum of the Monterey formation similar in texture 

 to the stone which is used for buildings, but different in color, 

 also contains casts of Tellina congesta in great numbers" 

 (p. 331). This is the only mention Blake makes of "Monterey 

 formation." or any similar expression, and it is evident from 

 the context that he was not naming a stratigraphic unit, but 

 simply meant the formation or type of material at Monterey — 

 a mere locality designation — a common practice among the geolo- 

 gists who explored the west at that period and for 20 or more 

 years later. 



As further evidence of this, it may be noted that Blake pub- 

 lished two geological descriptions of the territory about Monterey 

 flic following year (1856), without once mentioning these rocks 

 by such a designation. In the Pacific Railroad Report, 22 he 

 described them as "the Tertiary formations," and uses the term 

 Monterey only in the following expressions, "the base of the 

 formation at Monterey," "A stratum of the Monterey rock" 



-- Reports of Explorations and Surveys to ascertain the most practi- 

 cable and economical route for a railroad from the Mississippi River to the 

 Pacific Ocean. Vol. 5 (1856), Part II, Chapter XIII, esp. pp. 180-182. 



