Question

A broad plain formed by the joining of very gently sloping, and typically concave, inclined bedrock surfaces is known as what?

Answer 1

Pediplain
The surfaces which join to form pediplains are well known from the western United States, and also found along the forearc of the South American Andes and in South Africa. Pediplains are sparsely covered with soil, where they are not bare rock, and are usually formed in arid or semi-arid climates.