Several years back I found two carved grids deep in an Ohio cavern. The cavern could have been sealed the duration of the Holocene until two boys were hunting rabbits in the 19th century and discovered an entry.
Some of the entry ways are still packed with glacial mud/slurry visible from inside the cave. It has remained gated off and owned by the same family. They say no artifacts have ever been found there. There is easy to access chert, even a "Chert Room," which was was never mined. So the Ohio carved grids could possibly be pre-Wisconsinin glaciation in age.
The Ohio grids overlook a view onto a flowing underground river. Carved grids from Koonalda cave, Australia, also have an underground river.
Then a couple years ago Clive Finlayson's team at Gibraltar's Gorham cave reported a grid similar to the Ohio cave ones I found and attributed it to Neanderthals because it dated to just before the supposed arrival time of "anatomically modern humans" in Europe. The Ohio and Gibraltar grids are both on flat stone "tables" which rise from the cave floors.
This Virginia incised stone exhibits a grid in the same art motif as the Ohio and Gibraltar cave examples. It is an example of 'portable rock art' with a culturally facilitated meaning to its maker.
The lines can only be made with the precision seen here by utilization of a straight edge to guide the incising stone. The undulating line seems to have some free-hand features but could also have been made by a "slipping straight-edge" technique where the straight edge is shifted during the carving. This carving, or the process to make it, probably had a significant meaning to its maker.
"Prehistoric Engravings with Crosshatch Patterns
Home to some of the earliest known prehistoric art in all of Africa, the archeological site known as Blombos Cave is located in a limestone cliff, some 100 metres from the sea on the coast of South Africa, about 180 miles east of Cape Town. It is famous for its prehistoric rock engravings, dating back to the Mousterian period of the Middle Paleolithic era (70,000 BCE), which puts it among the oldest Stone Age art ever discovered. (See Oldest Stone Age Art: Top 100 Works.) The find consisted of two pieces of ochre rock incised with geometric abstract signs, and a series of beads made from Nassarius kraussianus shells."
Archaeology's attempts to ignore, marginalize or cover up the Arkfeld Site show it remains unscientific, agenda-driven and incapable of processing information about "Old World style" art and tool finds in North America. Witness a self-described "hick farmer from Virginia" who has you beat.