1855.] 329 



was considered to be infusorial.* A small piece, on being subjected to examina- 

 tion by the microscope, was found to contain innumerable discs and long cylin- 

 drical spicule and ring-like organic remains. A portion was then forwarded 

 to Prof. J. W. Bailey, of West Point, who, in his letter of acknowledgement, 

 thus remarks : lt The specimen from Monterey is rich in marine diatoms ; the 

 seive-like discs belong to the genus Cascinodiscus, but there are many other 

 very beautiful forms present. It is singulai that the deposit contains some species 

 which have only recently been detected as living species in the Pacific. It has 

 quite a modern look, and contains many species which could only have grown 

 in shallow water." 



I soon afterwards visited Monterey and examined the deposit. It is about two 

 miles distant in a south-east direction from the centre of the town, and forms a 

 portion of a hill which fronts the bay and rises on the east side of the stage-road 

 to San Francisco. This hill is between 500 and 600 feet high, and it is separated 

 from the bay by a broad, sandy plain, and a belt of sand-hills along the beach. 

 Groves of oak trees are found around the base of the hill, but towards its top it 

 is covered with a dense growth of chamisal,f throughjwhich the outcrop of the 

 white earth can be seen as a white spot on the hillside from all parts of the 

 town and the anchorage. On arriving at the locality, however, the white spot 

 which appeared so limited when viewed from the town, is found to have a length 

 of about one hundred feet, and a width of from 15 to 40. lt is also seen to ex- 

 tend in all directions under the vegetation by w r hich it is partly obscured. The 

 glossy green leaves of the shrubs which grow up about its borders, contrasted 

 strangely with the white, chalk-like earth, which seemed as little fitted for vege- 

 tation as a lime-heap. The weathering of the formation has loosened small 

 blocks and fragments, which lie upon the surface and hide the stratification from 

 view, so that it at first appears as a homogeneous mass of vast extent ; but on 

 breaking out some large blocks from a favorable exposure, the lines of stratifica- 

 tion became evident, and on a closer inspection they were seen to be as numerous 

 and thin as the leaves of a book. 



This out-crop appears to be the principal stratum, and it is near the top of the 

 hill ; but lower down a succession of strata are found alternating with siliceous 

 beds, which are peculiarly compact and very finely stratified. Some of these 

 are excessively hard, and break with a conchoidal fracture like flint or semi-opal. 

 The whole form a series of parallel strata which are not horizontal, but dip south 

 of east, or nearly south-easterly, at an inclination of from twenty to thirty de- 

 grees. The following is the succession of the strata from the upper stratum 

 downwards to the lowest point examined. 



The thicknesses stated are approximations. 



Section. 



1. White siliceous earth, light and charged with infusoria 



2. Compact and siliceous, probably bituminous, 



3. White and earthy, resembling 1, 



4. Compact, siliceous, dark colored and bituminous, 



5. White and earthy, like 1, ...... 



6. Compact, siliceous, dark colored and bituminous, 



7. White and earthy, like 1, ...... 



8. Compact, flint-like, very hard and nearly white. In thin layers, 2 



9. Thin layers of white earthy material, similar to No. 1 ; inter- 

 calated with thin sheets of compact and s^mi-opaline silica, 10 



10. Compact and siliceous. Hard and drab-colored, . . 3 



11. White and earthy, similar to No. 1. (The thickness of this 

 stratum was not estimated; it extends downwards, under the 

 chamisal, for a long distance.) ..... 



It will thus be seen that there is one bed of microscopic organisms 50 feet in 



* This specimen was collected by A. S. Taylor, Esq., of Monterey, and for- 

 warded to Dr. J. B. Trask, from whom 1 received it. 

 j- A low green growth of dwarf oaks or other shrubs. 



