The Joppa Pans are visible only at low tide.

The coal seams in these rocks were mined out by the Romans (I'm sure I read that - somebody correct me if i'm off track) - this is where the rock structures that contain the Lothian coalfields meet the sea (well at surface level). See here for more detailed geological information.

And more recently the Pans were used in the production of salt. By recent we're taking about from the 15th century through to the 1950's. Today only 2 buildings remain on the site of the Joppa Salt Pans - a cottage (oldest building in Portobello) and a hotel (with bar and restaurant). The hotel was originally the house of the salt works owner.