In
geology
Geology (). is a branch of natural science concerned with the Earth and other astronomical objects, the rocks of which they are composed, and the processes by which they change over time. Modern geology significantly overlaps all other Earth ...
, a lens or lentil is a body of
ore
Ore is natural rock or sediment that contains one or more valuable minerals, typically including metals, concentrated above background levels, and that is economically viable to mine and process. The grade of ore refers to the concentration ...
or
rock that is thick in the middle and thin at the edges, resembling a
convex lens
A lens is a transmissive optical device that focuses or disperses a light beam by means of refraction. A simple lens consists of a single piece of transparent material, while a compound lens consists of several simple lenses (''elements'') ...
in cross-section.
To thin out in all directions is to "lens out", also known as "lensing". The adjectives "lenticular" and "lentiform" are used to describe lens-like formations. Lenticle is a synonym for lentil, but may also refer to a fragment of rock that is lens-shaped. "Lenticule" is used for small lentil.
A lentil may also refer a minor unit in a formation of rock, similar to a
member
Member may refer to:
* Military jury, referred to as "Members" in military jargon
* Element (mathematics), an object that belongs to a mathematical set
* In object-oriented programming, a member of a class
** Field (computer science), entries in ...
but not generally spread out over a large geographical area. In this usage, the lentil thins out towards its edges.
is a special form of rock
interbedded mudrock
Mudrocks are a class of fine-grained siliciclastic sedimentary rocks. The varying types of mudrocks include siltstone, claystone, mudstone and shale. Most of the particles of which the stone is composed are less than and are too small to ...
and
cross-laminated rippled sandstone
Sandstone is a Clastic rock#Sedimentary clastic rocks, clastic sedimentary rock composed mainly of grain size, sand-sized (0.0625 to 2 mm) silicate mineral, silicate grains, Cementation (geology), cemented together by another mineral. Sand ...
. The lenses or ripples in lenticular beds are discontinuous in all directions.
See also
*
References
Petrology
Sedimentology
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