| 释义 |
offlap Geol.|ˈɒflæp, ɔː-|
Also off-lap.
[f. off adv. + lap v.2, after overlap v. 3.]
A progressive diminution in the lateral extent of conformable strata in passing upwards from older to younger strata, so that each stratum leaves a portion of the underlying one exposed; a set of strata exhibiting this.
1913A. W. Grabau Princ. Stratigr. xviii. 734 (caption) Diagram illustrating regressive overlap (off-lap) and the formation of a sandstone of emergence..into which the shore-ends of the successive members of the retreatal series..grade. 1948Jrnl. Geol. LVI. 147/1 Marine blanket sands represent the horizontal welding of many parallel prismatic shore lines during a long, continuous period of over-lap or off-lap. 1969Bennison & Wright Geol. Hist. Brit. Isles i. 14 The offlaps of marine sedimentation are accompanied, in this case, by lateral and vertical gradation into beds of continental facies. 1975Nature 10 Jan. 107/1 The stratigraphic relationship of the Devensian Tills of eastern England is therefore one of offlap..and not of overlap.
So ˈofflapping ppl. a.
1906A. W. Grabau in Bull. Geol. Soc. Amer. XVII. 615 Examples of regressively overlapping or, better, offlapping formations are frequently met. 1921― Textbk. Geol. I. xvii. 559 If, after a retreatal movement of the sea and the formation of an offlapping series.., a transgressive movement with overlapping of formations should follow, the sandstone bed of emergence would be in part reworked. 1974Nature 15 Nov. 200/1 The sealevel curve is based on the series of transgression-regression cycles identified from successions of offlapping coral reefs. |