Why Does This Rock Look Like This?

If you ever come across a rock that looks like the one in this photo, and wonder why part of it is missing, and other parts of it remain, there is a pretty easy explanation. And it all has to do with erosion.

why rock look like this
Do you know why this rock looks like this? (u/0hshitwaddu9)

Differences in Hardness

The most common reason, and most simple explanation for the rock looking like this is due to differences in hardness. The lighter material is likely softer and less resistant to weathering and erosion compared to the darker material.

Softer rocks erode more quickly when exposed to weathering processes such as wind, water, and temperature changes. This difference in erosion rates can create an overhanging shape where the harder, more resistant rock remains intact while the softer rock erodes away.

However, there are other factors that might also contribute to the different rate of erosion, which would result in the rock to look like the one in the photo.


The lighter material may have a different mineral composition, making it more susceptible to chemical weathering. For example, if the lighter layer contains more calcite (common in limestone), it would dissolve more readily in slightly acidic rainwater compared to a darker, silica-rich material like chert or basalt.

Porosity and Permeability

The lighter material might have higher porosity and permeability, allowing water to penetrate and weather the rock more easily from the inside. This internal weakening can accelerate erosion.

Environmental Exposure

The rock’s exposure to the elements can also play a role. If the lighter material is more exposed to direct sunlight, rainfall, or wind, it will weather more quickly. The darker material, being more resistant, will act as a protective cap, slowing down the erosion of the underlying lighter material.

Mechanical Weathering

Physical processes such as freeze-thaw cycles can exploit differences in the physical properties of the rock layers. Water entering cracks in the lighter material can freeze and expand, causing pieces to break off more easily than in the denser, more robust darker material.

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