It's nature's "fault" this tunnel is closed?
Several major geologic fault lines run under these mountains. The mountainside here is slowly shifting along a fault line into the right side of this tunnel, collapsing it.
The tunnel runs through rock known as "argillite", a highly compressed siltstone over a billion years old. Is it any wonder it has developed a few cracks?
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The Milwaukee Road was a much a road of stone as a road of steel.
The rails and ties on this part of the line sat on a rock bed of distinctive, colorful quartzite ballast mined from quarries 85 miles away in Montana.
Ballast kept the railroad ties in place, distributed weight from passing trains, allowed water to drain and protected against frost heaves. Over 80 percent of the rail-trail surface you're on is reused ballast.
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The Yeas and Neighs?of Track Width
Some say ancient, Imperial Romans originated the 4 foot, 8½ inch "Standard Gauge" spacing for wagon wheels by designing their war chariots and carts to uniformly fit behind the behinds of two Roman warhorses. And that centuries later railroads inherited this unique spacing. Well, maybe?
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