astyllen

from The Century Dictionary.

• noun A small temporary dam or partition, made either of branches or twigs interlaced, or perhaps sometimes of a simple piece of board, and used either to check the flow of water under ground or to separate ore from refuse or attle on the surface.

from the GNU version of the Collaborative International Dictionary of English.

• noun (Mining) A small dam to prevent free passage of water in an adit or level.