human
Produce a detailed written description of a gloomy scene outside a coastal area with sand, basalt, and boulders.
assistant
Once at sea level, now only entrenched at high tide, the wide mouth of a shallow cave is an open, jagged, teeth-like formation of broken basalt. Black sand, a combination of the rock particles and ancient lava formations shattered when it reached the cooler sea, is deposited from one end to the other of this narrow beach. Neither the moonlight nor a pair of larger flickering torches pierce beyond the dark opening, and a tumble of boulders prevents further access.