1) The Maya
2) Cahokia - The relics of an entire civilization are sitting underneath East St. Louis, Illinois. According to Gizmodo, Cahokia once housed up to 40,000 people and contained some 100 mounds made of dirt.
3) Easter Island
4)The Minoans
Thanx for adding the civs names!
Easter Island is fairly well understood. They starved themselves when they over used the land to the point where it became useless for growing things.
My understanding of the Minoans is that they might have been wiped out by an outside force, similar to the Turks if not the Turks themselves.
I went to high school west of St. Louis and, funny thing is, we never studied this civilization at all.
The Google satellite image shows a horseshoe lake adjacent to the burial mounds site. Maybe they were wiped out in one of the big Mississippi floods that routinely sweep through the area.
Ancient civilizations were brutal:
Mound 72 might just be the most significant archaeological discovery at the site. During an excavation, human remains were discovered: a man in his 40s experts believe might have been an important Cahokian chief.Below his burial site experts found more than 250 other skeletons, sixty percent of which are believed to have been sacrificial killings or ritual executions. This was estimated due to countless bodies missing hands and skulls, more than fifty 21 year-old women found in neatly-separated layers, and finally a mass burial grave with over 40 men and women who appear to have been violently killed.
In fact evidence supports some were alive when they were buried, attempting to claw their way out of the mass of dead bodies.

The Minoans disappeared at the same time as what is now thought to be a meteor impact on a section of land near the North East shores of the mouth of the Jordan River. Minoan influenced artifacts have been found there as well as evidence of high heat exposure, burnt bones, microscopic iron spheroids that came from the instant searing of red blood cells that sprayed from exploding bodies as well as smashed buildings. Pottery was found where sections appeared to have been scorched into trinitite, a kind of glassy material found in sand after atomic explosions. The meteor appeared to come in from the southwest and destroyed multiple cities and villages in a 400 square mile area on that eastern side of the Jordan river’s mouth and adjacent plains.
In short God took out the Minoans when he took out the cities of Sodom and Gomorrah!
But but Mittens and Beck are angry because there’s no mention of the Nephites and Lamanites... /s
(let me add a few more to be sure)
/s /s /s
A great civilization buried beneath East St. Louis? Talk about cultural regression!
Easter Island is called Rapanui by the natives. Oh wait ...