The a 6,000-mile-long crack in the earth's crust that divides parts of eastern africa into two sections.

Great Rift Valley hope this helps you out:)

Geothermic gradient is the rate of increasing temperature with respect to increasing the depth in the earths interior. away from tech tonic plates boundaries, it is about 25-40 c/km (72-87 degrees f/mi) of depth near the surface in most of the world.

1. antarctica2. saudi arabia