All that nature can never do, part VIII: sedimentary structures
A few examples of what Mr. Osmanagic would probably call "artifacts...
"Mud-cracks"
Southwestern Virginia, USA
Lac du Salagou, Hérault, France
St. George, Utah, USA
Photo Calvin J. Hamilton - Source
Klingenthal, Vosges, France
Newfoundland, Canada
Photo John W.F. Waldron - Source
"Flute casts", "groove marks", "tool marks" and "load casts"
Load cast, Cheshmehanarak, Iran
Flute cast, Nord-Est Iran
Flute cast, Kadkan, Iran
Flute cast, Tafilalt, Maroc
Groove mark, Surenenpass, Suisse
Groove mark, Rudawka Rymanowska, Pologne
Tool mark, Liscomb Island, Canada
Photo John W.F. Waldron - Source
Flute casts, Gaspe Peninsula, Quebec, Canada
Flute casts, Gaspe Peninsula, Quebec, Canada
Flute casts, Salton Trough, southern California
"Molds", imprints from concretions or crystals
Nova Scotia, Canada
Photo John W.F. Waldron - Source
Empreinte de cristaux dans du grès, France
Jaizkibel, pays basque, Espagne