A small new lava plain had been formed.

The Hesperian period is marked by the formation of extensive lava plains.

The lava plains are treeless and for the most part too dry for agriculture.

Besides the lava plains, representing about 60 percent of the surface, the planet's topography seems to fall into three main categories, project scientists said.

Already the lava plain was humping like a slow ocean swell, as if trying to break free of its cool crust.

The Falls are unexpected after driving west across gently undulating lava plains.

Most are partly buried by younger lava plains, making their sources difficult to identify.

The only remaining visible edifice is a pyramid, half buried under the far edge of the lava plain.

The park by this time was a relatively featureless and large lava plain.

The southern and eastern shores are flat lava plains.