Their route took them on a gradual decline into the flat basin of the vale.

The nest is around 2.5 m (eight feet) wide and 30 cm (one foot) deep, and is constructed as a relatively flat basin of sticks.

Most of the Ténéré is a flat basin, once the bed of the prehistoric Lake Chad.

The slope of the land increased noticeably beyond the last flat basin.

This area is part of the basin and range geologic region, characterized by linear mountain ranges which are separated by broad, flat basins.

The streambed widened, opening out into a flat basin.

To the west, a flat and smooth basin, broken by craters.

Now, it's just a huge, relatively flat basin that is more or less a 'trunk' for dozens of smaller canyons that branch off it.

It has been argued that there is little consequence to subsidence in a wide, flat, agricultural basin, since the settlement is uniform.

It is surrounded mostly by mountains, although the city hall is located in a flat basin.