| 释义 |
duricrust Geol.|ˈdjʊərɪkrʌst|
[f. L. dūr-us hard + -i- + crust n.]
A hard crust formed at or near the surface in a semi-arid climate by the accumulation of mineral matter, esp. silica or iron oxides, deposited as ground water rises by capillary action and evaporates; esp. such a crust in Australia.
1928W. G. Woolnough in Jrnl. & Proc. R. Soc. N.S.W. LXI. 27 From the fact that..the chemically formed covering..always appears as a relatively hard ‘armour plate’, protecting softer, decomposed rock residue beneath it, I propose to group together all the representatives of the hard crust, in every part of Australia where they can be shown to have formed in the same manner, during the same geological period, under the name of the duricrust... [Note] This name was suggested to me by Professor Todd, Professor of Latin in the University of Sydney. 1954W. D. Thornbury Princ. Geomorphol. iv. 83 Under the present arid conditions which prevail today [in Australia] duricrusts are not forming in a significant amount but rather are undergoing destruction. 1955P. A. Buxton Nat. Hist. Tsetse Flies xi. 390 The thicket grows on a clay cement or duricrust, which may well be too hard for the larva to enter. 1962L. C. King Morphol. of Earth vi. 172 The duricrust often grades down through a zone of weathered rock into the bedrock itself. 1977A. Hallam Planet Earth 85 At other times (pluvials), average rainfall may have been markedly greater so that..bedrock became deeply weathered to give striking weathering crusts (duricrusts). 1978T. Langford-Smith Silcrete in Australia i. 2 Differences in the type of duricrust..were regarded by Woolnough as a reflection of changes in the rock type, so that whether a duricrust happened to be ferruginous or siliceous was a measure of the underlying parent material.
Hence ˈduricrusted a., covered with a duricrust.
1962L. C. King Morphol. of Earth vi. 172 Most duricrusted lands are subject to an annual period of drought (Africa, Australia). 1978T. Langford-Smith Silcrete in Australia i. 2 Woolnough's conception of a single duricrusted surface was over-simplified. |