The longest natural erosion arch in the Alps (at 32 metres, and a double one at that) was only discovered in 2005, in the Chartreuse mountain chain above Grenoble, at the southern tip of the Jura mountains (part of the Pre-Alps), long famed for the bittersweet herby alcohol produced by the Carthusian monks (reputedly some of the most austere, meditating in their isolated eyrie, where they have been based since 1084). The find was made by a hiker who was researching a book on the hidden unknown treasures of the range, later published as Chartreuse inédite : Itinéraires insolites.
Unless they are volcanic basalts, black rocks tend to mean one thing to a geologist: an absence of rotting, and quite often a hard time for life. It denotes a period where the ground or sea bottom was poor in oxygen, as happens in the current day in peat bogs, some deltas where sediments bury the organic matter quickly or in stratified lakes or basins such as the Black Sea.
Rocks might live for a long time compared to our biblical three score years and ten, but in the same way that organisms live, die and decay, thereby replenishing the soils with organic materials and nutrients such as phosphorous (called life’s bottleneck by Isaac Asimov) for the next cycle of life, so do rocks go through cycles of existence. A lava erupted in an oceanic spreading ridge, or sediments deposited by river, wind or glacier can enter new incarnations as very different rocks after the heat and pressure of being buried in the Earth or involved in a mountain building event has had its effect.
These transformations are called metamorphism, and are graded by the estimated temperature / pressure conditions under which they occur, with a variety of index minerals of similar composition providing the means to assess them.
Ever gone cave diving several hundred meters beneath the surface of the ocean in a location in Albania with incredibly clear water? If you haven’t, check this out. Great views of life in the upper portions of the cave giving way to sedimentary limestone layers, deposited on the edge of the Tethys Ocean (and now eroding) as they go down.