paleosol definitions etc.
Posted by Howard Hobbs 09 Sen 1999 00:24:08 I agree with a lot of Vance Holliday's comments of 7 September, but I would like to point out some different perspectives, as well correct a clear error. Although it is true that geologists call a lithified sand a sandstone regardless of age or hypothetical origin, it is equally true that degree of lithification plays no part in the stratigraphy of sediments. Diagenesis is post-depositional and more or less irrelevant to the stratigraphy. Both lithified and unlithified sediments can be "rock-stratigraphic" units. If lithification is not a big deal for geologists, why should it be for pedologists? Yes, lithification is something that can be recognized in the field, but I can't see that it's useful to specify. If you are describing a lithified sedimentary sequence with buried soils, it stands to reason that they would be lithified too. If "paleosol" is not useful for anything else, why use it here? There is also an etymological quibble; "paleo" doesn't mean "hard", it means "old". The two are not the same; although older sediments tend to be more lithified, you can find Cambrian sandstones that barely deserve the "stone" designation. A geosol has to be buried where it is defined; otherwise, its stratigraphic position cannot be recognized. But it is still the same geosol where it can be traced to an area where it is not buried (or where it is exhumed). So this objection is not valid. As for its relative lack of use, people don't have to use it if they don't want to, and I guess a lot of people don't. Myself, I could use Soil (capitalized) in place of Geosol, if that is the consensus. But Geosol does offer a slight edge in clarity, because it specifies a soil-stratigraphic unit. Soil scientists use soil (lower case) informally in the sense of soil series, as in the "Lester soil". Some things are hard to define because they are inherently complex, or inherently fuzzy. Some concepts are fairly easy to explain, but not to define. To explain something, you need to get the basic concept across, but you don't have to get all the details right. I think a lot of what Vance Holliday calls definitions of paleosols are really explanations. A definition, on the other hand, is a line that separates what is defined from everything else in the world. Here you have to get very picky, and arguments can go on indefinitely. Everyone knows what war is, but how do you define it, unambiguously but at the same time concisely? For that matter, what is the clear concise definition of soil?
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