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CHAP. VI.
POST-TERTIARY STRATA.
339
The following diagram exhibits the comparative characters and relations of the several regions:—
| Sea Bottom— Deposits forming. |
Region. | Extreme Depth in Fathoms. | Characteristic Animals and Plants. |
12 Feet—Ground various, usually rocky or sandy, conglomerates forming.
|
I. | 2. | Littoriua cserulescens. Fasciolaria tarentina. Cardium edule. Plant:—Padina pavonia. |
Ground muddy, sandy, or rocky.
|
II. | 10 | Cerithium vulgatum. Lucina lactea. Holothuriae. Plants:—Caulerpa, Zostera. |
Ground mostly muddy or sandy: mud bluish.
|
III. | 10 | Aplysiæ. Cardium papillosum. |
Ground mostly gravelly and weedy, muddy in estuaries.
|
IV. | 35. | Ascidiae. Nucula emarginata. Cellaria ceramoides. Plants: Dictyomenia volubilis. Codium bursa. |
Ground full of nullipores, and shelly.
|
V. | 55 | Cardita aculeata. Nucula striata. Pecten opercularis. Mvriapora truncata. Plant: Rityphlæa tinctoria. |
Ground mostly nulliporous, rarely gravelly.
|
VI. | 79 | Venus ovata. Turbo sanguineus. Pleurotoma maravignæ. Cidaris hystrix. Plant:—Nullipora. |
Ground mostly nulliporous, rarely yellow mud.
|
VII. | 105. | Brachiopoda. Rissoa reticulata. Pecten similis. Echinus monilis. Plant: Nullipora. |
Uniform bottom of yellow mud, abounding for the most part in remains of Pteropoda and Foraminifera.
|
VIII. | 230 | Dentalium 5-angulare. Kellia abyssicola. Ligula profundissima. Pecten Hoskynsi. Ophiura abyssicola. Idmonea. Alecto. (No plants). |
Zero of animal life probably about 300 fathoms.
