The Alport Castles are a landslip feature in the Peak District National Park in Derbyshire.

[3] About 300 million years ago, the area now known as the Peak District was part of a river delta that flowed into the sea.

Further turbidite flows eroded into previous ones, resulting in the type of deposit seen at Alport Castle.

In the Peak District this coarse material is the gritstone that caps high points, protecting them from erosion.

One theory is that the soft shales below are too weak to support the weight of the heavy sandstone above and collapse under it, or that, because water can run through gritstone but not shale rock, trapped water may have "lubricated" the rock to the point where one layer slid over another, causing the landslide.