Here's why:

* Particle size: Clay particles are much smaller than sand particles. This makes them more susceptible to being picked up and carried away by wind and water.

* Structure: Clay soils tend to have a dense, compacted structure, which makes them less resistant to erosion. The small particles can clump together, forming a crust that can easily be broken and washed away.

* Water infiltration: Sandy soils have larger pores and better drainage, allowing water to infiltrate quickly. Clay soils, on the other hand, have smaller pores and tend to hold water, making them more vulnerable to runoff and erosion.

In summary:

* Sandy soils are more resistant to erosion due to their larger particle size, good drainage, and ability to hold together well.

* Clay soils are more susceptible to erosion due to their small particle size, dense structure, and poor drainage.

It's important to note that erosion can be influenced by various factors, such as rainfall intensity, slope, and vegetation cover. However, in general, clay soil is more prone to erosion than sandy soil.