51�Թ�

(of a bird) resting on a perch, such as a branch, telephone wire, or fence, or a rod specially designed for the purpose.

settled or resting in a relatively high position, like a bird on a perch.

Geology.��(of a boulder or block) left on the top of a hill, ridge, etc., by ice that melted after carrying it there.

Geology.��

1. (of a lake) having a surface level at an unusually high elevation, well above that of aquifers and other bodies of water in the area, because it has formed on a dense, hardened layer of sand mixed with organic matter that traps water on top of it.

   Half of all the world’s known perched lakes are found on Australia’s Fraser Island.

2. (of an aquifer) occurring above the regional water table, having been formed by an accumulation of groundwater that cannot permeate the underlying layer of clay or other dense soil.

   Perched aquifers are sometimes good water sources, but they tend to be relatively small and easily depleted with overpumping.