Significados de underlain with en inglés

The territory underlain with this natural gas has not yet been clearly defined.

Such fossil lakes are marked by swamps or level meadows underlain with muck.

There are quicksands along the Flathead, sands underlain with water, apparently secure but reaching up clutching hands to the unwary.

Other things being equal, which will afford the larger proportion of run-off, a region underlain with granite rock or with coarse sandstone?