Mountain creation has always been a heated topic of interest, and one that has relied on ancient data to provide answers to those hoping to understand the phenomenon that takes centuries and millennia to occur. Geochemists from Stanford University have used raindrops, or more precisely the isotopic residue of raindrops, to shed light on the creation of the mountain ranges along the West of North America.
According to the research, mountains began poking their way up through the crust some 50 million years ago, in southern British Columbia. The following 22 million years saw a wave of mountain building sweep down the west of the North American continent as far south as modern-day Mexico and as far east as Nebraska.
The raindrops had fallen between 65 and 28 million years ago and been incorporated into clays and carbonate minerals on the surface, or in volcanic glass, keeping the data available for use.
Findings such as this have helped dispel the myth that North America was home to a Tibet-like mountain range which subsequently collapsed and left the relatively smaller mountains in their place. As it was, the mountains reached some 4 kilometres high, or 14,000 feet, rather than the average elevation of 15,000 feet some had theorized.
The isotopic data showed that there was a big uplift in the region, specifically in southwest Montana around 49 million years ago, “and another one at 39 MYA, in northern Nevada” said Hari Mix, a doctoral candidate in Environmental Earth System Science at Stanford, who worked with the analyses of about 2,800 samples collected by his team or from previous research. This data corresponds to a wave like progression which took place underneath the North American plate as the Farallon plate was shoved underneath and began peeling away from the underside of the continent.
“The peeling plate looked sort of like a tongue curling down,” said Page Chamberlain, a professor in environmental Earth system science who is Mix’s advisor.
As hot materials poured in after peeling plate, the heat and buoyancy forced the land to rise in elevation, and as the peeling tongue continued to fall off, and the hot mantle flowed in behind it, a slow-motion wave of mountain building slid southward.