Reading something on Facebook by Ru Smith reminded me of this story about the demise of one of Cleveland's (now Yorkshire) more prominent land marks.
The hill was originally a "Sugar Loaf", outlying the North Yorkshire Moors. The geology is sandstone laid down in the middle to late Jurassic era - to around 170 million years ago, with a featuring hard conical cap.
During the late nineteenth century there was considerable alum and ironstone mining going on in the area, including the hill itself; this until 1912 when either a fault slipped or mine workings gave way and the whole summit collapsed.
Today the hill is owned by the National Trust with a distinct crater to one side - because of the new shape often referred to as the Yorkshire Matterhorn.
The other feature of this place are the incredibly well preserved fossil leaves and flora, appearing like they have been in a flower press for 170 million years - see last photo.
Must go back some time!