They have roots to support them, and most of it is hidden below the surface of the earth, similar to most of a glacier being hidden underwater.
(most of it; is hidden; L:below the surface of the earth, similar to most of a glacier being hidden underwater) (They; have; roots to support them) Context(They have,List([0, 9))):(They; have to support; them)
They have,List([0, 9))
most of it They They
is hidden have have to support
L:below the surface of the earth, similar to most of a glacier being hidden underwater
roots to support them
them