Roof of an ancient volcano
It erupted in middle and late Jurassic (around 150 mln years ago), being just an island in the Tethys Ocean. Earth was a very different place back then - there was no Black Sea, no Mediterranean, much of Europe was flooded under shallow waters.
It all started with liquid lava flows on the seabed. Later, composition of magmas has changed and it turned into stratovolcano, shaking its neighborhoods with explosive eruptions.
Then - sea waters have receded and the Crimean Mountains have risen; now its dark-grey rocks are embedded into the white limestones of the peninsula's southern coast. The Kara-Dag -- the Black Mountain. Ragged by time but still dominating the surroundings.
Now, it's the Karadag Nature Reserve, a paradise for geologists with some interesting wildlife as well. See in Google Maps.