I was recently sent this stunning photo of a slate open quarry in China. The image has not been rotated! Look at the workers who are standing – they are vertical!
This photo dramatically shows the angle of dipping of the slate vein, dictating this particular method of extraction.
Open quarries follow the vein on the slope of the mountain and use this gallery mining system. It is not at all uncommon to find examples of more than one method of extraction within the same quarry. Click here for a previous post which explains these methodologies in more detail.