What Covers the Desert?

Contrary to the common image of endless sand dunes, bare earth covers the majority of deserts.

While sand is certainly present in many arid regions and forms the iconic dunes, it is not the dominant surface cover across all deserts globally. The reality, as highlighted by information from various sources, is that 80% of deserts are not covered in sand.

Bare Earth: The Predominant Desert Surface

Instead of sand, the vast majority of desert landscapes are characterized by bare earth. This exposed surface often reveals:

• Bedrock: The solid rock layer beneath the soil.
• Clay: Fine-grained natural rock or soil material, often dry and cracked in deserts.

This bare earth is a result of specific climatic conditions and unique erosion patterns that shape these dried-out ecosystems. The lack of significant vegetation allows the underlying geological structure to be exposed.

Diverse Desert Surfaces

Although bare earth is the most common cover, deserts exhibit a variety of surface types depending on their geology and climate history. These include:

• Sand Deserts: Areas dominated by sand dunes, covering about 20% of global desert areas.
• Pebble Deserts (Regs or Serirs): Plains covered with tightly packed pebbles and stones, often left behind after wind erosion removes finer materials.
• Rock Deserts (Hamadas): Plateaus or mountains with exposed bedrock surfaces.

These different types of covers illustrate the diverse nature of desert environments, extending far beyond just sand.

Understanding Desert Terrain

Knowing what covers the desert is key to understanding these extreme environments. The surface type influences:

• Temperature: Different materials absorb and reflect heat differently.
• Water Flow: How water moves (or doesn't move) across the landscape during rare rain events.
• Erosion: The processes that shape the land, primarily wind and occasional water.

Here is a simplified look at the primary covers:

This table reinforces that while sand is notable, bare earth represents the vast majority of desert surface area.