. Bulletin of the Museum of Comparative Zoology at Harvard College. Zoology; Zoology. Fig. 180.—Radiolarian ooze (Murray). "j5. Fig. 1S4. — Diatom ooze (Mirrray). ^^-. organisms, which have likewise fallen from the surface waters. A radiolarian ooze has hitherto been met with only in the deep- est waters of the Western and Central Pacific, and diatom ooze appears to be confined to the Southern Ocean, a little north of the Antarctic Circle. Thus it will be seen that the character of a marine deposit is largely determined by its distance from land, and again by the nature of the organisms l
. Bulletin of the Museum of Comparative Zoology at Harvard College. Zoology; Zoology. Fig. 180.—Radiolarian ooze (Murray). "j5. Fig. 1S4. — Diatom ooze (Mirrray). ^^-. organisms, which have likewise fallen from the surface waters. A radiolarian ooze has hitherto been met with only in the deep- est waters of the Western and Central Pacific, and diatom ooze appears to be confined to the Southern Ocean, a little north of the Antarctic Circle. Thus it will be seen that the character of a marine deposit is largely determined by its distance from land, and again by the nature of the organisms living in the surface waters. The dead shells of pteropods, of foraminifers, of radiolarians, and of diatoms are heaped up on the bottom, some in one part of the ocean, some in another; and as no other materials reach these distant regions to cover them, they form characteristic deposits. Depth is, however, an important factor in reference to the com- position of a deposit in any locality. There seems to be now no doubt that the whole of the carbonate of lime shells, such as those of mollusks and foraminifers, are entirely removed by solution in very deep water during their fall from the surface to the bottom, or immediately after reaching the bottom. It is found that, with increasing depth, the pteropod and heteropod shells are the first to disappear from deposits, then the more delicate surface foraminifera, and finally the larger and heavier ones. It is likewise observed, that the more numerous these shells are in the surface waters, the greater is the depth at which they will accumulate at the bottom. As a rule, a ptero-. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Harvard University. Museum of Comparative Zoology. Cambridge, Mass. : The Museum
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