(Geology)

An intrusive igneous rock formation, formed when magma forces its way between two horizontal rock strata, usually sedimentary rock, forming a layer (1) of more or less even thickness. A sill usually exists in relation to a vertical volcanic conduit(2) that connects it to the magma chamber or batholith (3) beneath it. The conduit usually continues above the sill to the surface; otherwise, magma forced in between the rock layers will have forced the rock layers upwards, forming a laccolith (4) instead of a sill.
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#  ##### # ##### ###########  #  # ### 3
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Sill (?), n. [OE. sille, sylle, AS. syl, syll; akin to G. schwelle, OHG. swelli, Icel. syll, svill, Sw. syll, Dan. syld, Goth. gasuljan to lay a foundation, to found.]

The basis or foundation of a thing; especially, a horizontal piece, as a timber, which forms the lower member of a frame, or supports a structure; as, the sills of a house, of a bridge, of a loom, and the like.

Hence: (a)

The timber or stone at the foot of a door; the threshold.

(b)

The timber or stone on which a window frame stands; or, the lowest piece in a window frame.

(c)

The floor of a gallery or passage in a mine.

(d)

A piece of timber across the bottom of a canal lock for the gates to shut against.

Sill course Arch., a horizontal course of stone, terra cotta, or the like, built into a wall at the level of one or more window sills, these sills often forming part of it.

 

© Webster 1913.


Sill, n. [Cf. Thill.]

The shaft or thill of a carriage.

[Prov. Eng.]

 

© Webster 1913.


Sill, n. [Cf. 4th Sile.]

A young herring.

[Eng.]

 

© Webster 1913.

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