A monolith is a geological feature such as a mountain, consisting of a single massive stone or rock, or a single piece of rock placed as, or within, a monument. Erosion usually exposes the geological formations, which are most often made of very hard and solid metamorphic or igneous rock.

A monolith is a monument or natural feature such as a mountain, consisting of a single massive stone or rock. Erosion usually exposes these formations, which are most often made of very hard and solid metamorphic rock. The word monolith derives from the latin word 'monolithus' and the Greek word 'monolithos', derived from 'one' or 'lonely' and 'stone'.

There are natural and manmade monoliths. They are found throughout the planet, under water and in space.

Ayers Rock - Uluru

Ayers Rock is the world's largest monolith rising 318m above the desert floor with a circumference of 8km. Depending on the time of day and the atmospheric conditions the rock can dramatically change color - blue red, purple ...

Utah's red rock metronome: Seismic readings reveal Castleton Tower's unseen vibrations   PhysOrg - August 26, 2019
A Utah rock formation called Castleton Tower gently vibrates, at about the same rate that your heart beats, keeping time and watch over the sandstone desert. Swaying like a skyscraper, the red rock tower taps into the deep vibrations in the earth - wind, waves and far-off earthquakes.

Monoliths in Pop Culture

The best-known cultural reference is to the Monolith from 2001: A Space Odyssey (film) by Arthur C. Clarke and Stanley Kubrick. In the series, the Monoliths are black ebon and transparent oblong slabs, fitting exactly into the ratio 1:4:9 (9 height, 4 width and 1 depth). They form part of a Solar-System-wide computer network planted by an alien civilization to monitor an experiment which culminated in humanity.

Monolith - '2001 A Space Odyssey

Creation - Thus Spoke Zarathustra - Eclipse - Crystalinks' Blog

Monoliths in Space

'Monolith' Object on Mars? You Could Call It That  
Live Science - April 15, 2012

Amateur stargazers have discovered an intriguing object jutting out from the surface of Mars. The seemingly perfectly rectangular, upright structure, found in NASA images of the Red Planet, bears a striking resemblance to the monoliths planted on Earth and the moon by aliens in the classic sci-fi film "2001: A Space Odyssey."

The object in question was first spotted several years ago after being photographed by the HiRISE camera onboard the Mars Reconnaissance Orbiter, a NASA space probe; every so often, it garners renewed interest on the Internet. But is it unnatural - a beacon erected by aliens for mysterious reasons, and even more mysteriously paralleled in the imaginations of Stanley Kubrick and Arthur C. Clarke, creators of "2001"? Or is this rock the work of nature?

According to Jonathon Hill, a research technician and mission planner at the Mars Space Flight Facility at Arizona State University, who processes many of the images taken during NASA's Mars missions, the object in question is no more than a roughly rectangular boulder.

The HiRISE camera that photographed it has a resolution of approximately 1 foot (30 centimeters) per pixel -impressive considering the 180-mile (300-kilometer) altitude from which it photographs the Martian surface, but not quite sharp enough to capture the cragginess of a mid-size boulder. "When your resolution is too low to fully resolve an object, it tends to look rectangular because the pixels in the image are squares.

The location of the boulder at the bottom of a cliff near many other boulders suggests it broke off the cliff and tumbled to its current spot sometime in the distant past, Hill said. Such a perilous location is itself an argument against deliberate placement by aliens: "If I was going to build a monolith somewhere, that's the last place I would put it!" he said. "The debris falling from the cliff would cover it up pretty quickly, on geologic timescales."

Hill added that the height of the boulder is being exaggerated in the photo by a low sun angle. Photographed when the sun was near the horizon, the boulder casts an especially long shadow.

The ufologists aren't necessarily wrong in calling it a monolith - the word simply translates from Latin as "one stone." But this monolith isn't the masonry of Martians.

Standing Stones

Standing stones, orthostats, liths, or more commonly megaliths (because of their large and cumbersome size) are solitary stones set vertically in the ground and come in many different varieties. Standing stones are usually difficult to date, but pottery found underneath some in Atlantic Europe connects them with the Beaker people; others in the region appear to be earlier or later however. Where they appear in groups together, often in a circular, oval, henge or horseshoe formation, they are sometimes called megalithic monuments. These are sites of ancient religious ceremonies, sometimes containing burial chambers

This is a standing stone I found in 1994 -
The California Chamber in Fahnestock Park, in New York

Monoliths   Wikipedia

List of monoliths around the world Wikipedia

Standing Stones Wikipedia