Which landform covers most of southwest australia?

Darling Scarp/Darling Range

Explanation:

The southwestern part of Australia is dominated by the Darling Scarp, often referred to as the Darling Range as well. The Darling Scarp is lifting up sharply from the lowlands along the coastline. It is not a high area, but it is considered as plateau, including also some smaller mountains on its edges.

This geologic formation is a very old one, and it is attributed to a fault that has existed there in the past. The fault though can not be seen nowadays as the Darling Scarp is eroded some 15 km to the east. The coastal plains around it are younger and they have formed from separate geologic activities.

This area is mostly arid and semi-arid. The climate is mostly hot and dry, with slight drops in temperature in some parts during the winter periods. It is an area mostly dominated with drought resistant shrubs and grasses.