sub-outcrop

English

Etymology

From sub- +‎ outcrop.

Noun

sub-outcrop (plural sub-outcrops)

  1. (geology) A rock stratum that was once exposed at an ancient erosion surface and unconformably underlies another rock stratum.
    • 1917, Cuthbert Baring Horwood, The Gold Deposits of the Rand, page 160:
      Beyond the eastern limit the outcrop dips below the Black Reef and Dolomite formations; but the sub-outcrop, sweeping round and striking south-east, has been traced by bore-holes for another ten or twelve miles.
    • 1924, Mining Publications (publisher), The Mining Magazine, Volumes 30-31, page 372:
      The sub-outcrop on the northern part of Rietfontein No. 4 and Benoni No. 3 is fixed by several bore-holes and by mine workings.
    • 1966, D.S. Parasnis, Mining Geophysics, page 147:
      Another interpretation is that the moraine cover is considerably thinner at the anomaly centre than at the drillhole sites so that the sub-outcrop of the ore actually occurs north of the position in which it is shown in Fig.50.
    • 1986, Maurice Slansky, Geology of Sedimentary Phosphates, page 50:
      Certain pellets are very homogeneous in appearance, with practically no endogangue; grains of this type are frequently contained in sub-outcrop strata.
    • 1991, Stephen A. Manydeeds, Bruce D. Smith, Mineral Frontiers on Indian Lands:
      This great abundance of surficial silica deposited in the five chalcedonic sinter terraces indicates that extensive sub-outcrop volumes of the Palm Springs formation and the Canebrake conglomerate have been saturated, soaked, and replaced by silica, thereby forming key gold target areas in Sections 20 and 30.
    • 2006, Gavin M. Hilson (editor), Small-scale Mining, Rural Subsistence and Poverty in West Africa, page 108:
      The government of Mali interprets artisanal mining as operations engaged in the extraction and beneficiation of mineral commodities sourced from primary and secondary deposits, outcrops or sub-outcrops, using manual methods and traditional processes.
    • 2015, Wolfgang Derek Maier, Raimo Lahtinen, Hugh O'Brien, Mineral Deposits of Finland, page 28:
      Subsequently, a low-altitude airborne geophysical survey was flown over the whole area, and the results were useful in determining the extent and structure of the carbonatite sub-outcrop.
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