The Amalfi Coast is primarily made of limestone, a sedimentary rock formed from the accumulation of marine organism remains.

Specifically, the cliffs and mountains of the Amalfi Coast are made from Miocene limestone, which formed approximately 23 to 5.3 million years ago. This limestone is characterized by its:

* White to light gray color

* Porous texture

* Presence of fossils, indicating its marine origin

The limestone formations have been shaped by:

* Geological uplift

* Erosion from the sea and rain

* Volcanic activity

These factors have created the dramatic and picturesque landscape of the Amalfi Coast, with its steep cliffs, narrow valleys, and hidden coves.