Last updated on Feb. 13, 2019
[link to www.flickr.com (secure)]
Photo shows columns at Crowley Lake in California, USA. There are about 5,000 such columns at the place (note 1). Some are under lake water. Some are buried under ground. Some are exposed as shown in the photo. Arrows in the photo point to different erosion:
Green arrows: Columns that are all exposed;
Red arrows: columns whose middle sections are surrounded with solid material;
Yellow arrows: columns whose upper sections protrude from solid material.
Some of the columns are shaped like segmented cylinders. For examples, see [link to www.flickr.com (secure)] [link to www.flickr.com (secure)]
[link to www.flickr.com (secure)]
There are no such columns elsewhere in the world. There is no evidence that nature formed these columns (note 1). If nature had formed the columns, why hadn't nature formed similar columns elsewhere in the last billions of years? Geologists say these columns are more than 700,000 years old (note 1). That age makes them prehistoric man-made columns.
Image source: [link to www.atlasobscura.com (secure)] (the ninth photo on the right side of the photostream)
Location on Google map: [link to www.google.com (secure)]

Note 1: see the last paragraph in [link to en.wikipedia.org (secure)]

See also: 1. Google search results for "cylinder at Crowley Lake": [link to www.google.com.tw (secure)]
2. video of the columns: [link to www.youtube.com (secure)]
3. human evolution: [link to en.wikipedia.org (secure)]