Fig. 1 Santorini - the vertiginous volcanic cliffs
How did Santorini form? A volcanic mountain, far bigger than Krakatoa, exploded and the centre of the island sand 200 to 300m. For the detail, the layers of rock, the difference kinds of volcanic formations, I'll need to drill a little deeper than the local tourist guide.
Fig.2 A chapel, church or cathedral around every corner
I estimate that you can't travel 200 yards without finding another chapel. And like the above, you find yourself descending the cliff face and find it leads to ... another chapel.
I sense the Easter Island effect here - anyone who could afford one financed its building? Or they were simply very religious.
Here for a family wedding. Its surprising how much reading and writing you can get done in the ample 'down time'.