layer vs sluice box

layer

noun
  • A single thickness of some material covering a surface. 

  • One of the items in a hierarchy. 

  • A person who lays anything, such as tiles or a wager. 

  • A (usually) horizontal deposit; a stratum. 

  • A shoot of a plant, laid underground for growth. 

  • An item of clothing worn under or over another. 

  • A mature female bird, insect, etc. that is able to lay eggs. 

  • A hen kept to lay eggs. 

  • one in a stack of (initially transparent) drawing surfaces that comprise an image; used to keep elements of an image separate so that they can be modified independently from one another. 

verb
  • To arrange in layers. 

  • To cut or divide into layers. 

sluice box

noun
  • A box with riffles along the bottom, used to trap heavier gold particles as water washes them and the other material along the box. 

How often have the words layer and sluice box occurred in a corpus of books? (source: Google Ngram Viewer )