Archaeologists called these presumed pioneers the Clovis culture, after distinctive stone tools that were found at sites near Clovis, New Mexico, in the 1920s and 1930s.
As caches of Clovis tools were uncovered across North America over subsequent decades, nearly all archaeologists signed on to the idea that the Clovis people were the first Americans.
The primary excavation has gone down to a level that dates to at least 50,000 B. Until increasing challenges in the first decade of the 21st century to the Clovis theory based on this site and others, it was unusual for archaeologists to dig deeper than the layer of the Clovis culture, as they then believed that no human artifacts would be found older than Clovis.
Among the objects from the "pre-Clovis" stratum, dated to 16,000-20,000 years BP, is a large piece nicknamed the "Topper Chopper." This apparent tool offers some of the most compelling evidence for human agency, including bifacial flaking of the edge. The site is somewhat hilly: the lowest section lies along the river at an elevation between 80 feet (24 m) and 90 feet (27 m), while the highest is the site's eastern edge, which rises above 130 feet (40 m).
Almost 14,000 years later, there is no way to tell how many hits it took to bring the beast to the ground near the coast of present-day Washington state.
But at least one struck home, plunging through hide, fat and flesh to lodge in the mastodon's rib.
Also, with no forced single supplements, you won't be charged any extra for travelling alone.
The oldest rock is Precambrian metamorphic rock that forms the core of the North American continent.
There is also Precambrian sedimentary argillite, dating back to 1.7 billion years ago.
The rocks of that older range were reformed into the Rocky Mountains.
The Rocky Mountains took shape during an intense period of plate tectonic activity that resulted in much of the rugged landscape of the western North America.