Minerals in the Mesas

The colorful cliffs here hide a plain, useful seam. The Dakota Formation, laid down in coastal swamps more than eighty million years ago, holds two things upper Bryce Valley put to work: thin bands of coal and a swelling clay called bentonite. Small mines dug the coal to heat local homes through the early 1900s. The clay had a stranger destiny — trucked south by the ton to Glen Canyon Dam, where it helped seal the coffer dam that turned the Colorado River aside. The seams are quiet now, the story left to this roadside sign.

What the plaque says

Dakota Formation’s Coal and Clay While the rock formations in this region often presented formidable travel obstacles for early settlers, they also supplied many useful natural resources. Locally, a rock layer known as the Dakota Formation (the bottommost layer of which is just visible atop the colorful Entrada sandstone cliffs before you) yielded two important resources — coal and bentonite clay. Created from the remains of lush, coastal swamps that covered this region more than 80 million years ago, thin coal seams in upper Bryce Valley sustained a handful of small mining operations that supplied heating fuel to area residents during the 1900s. In the mid-1900s, bentonite clay was also mined about a mile east of here. Bentonite clay can absorb many times its volume in water, a quality that has led to its use in many applications — from water storage and well drilling to cat litter and medicines. Bentonite In the late 1930’s, a Henrieville mine yielded thousands of tons of bentonite from these hills. Much of the bentonite was trucked to the Glen Canyon Dam site, where it was used to build a coffer dam that diverted the river so the main dam could be built. To facilitate transport, local men donated time and machinery to complete the Cottonwood Road from Cannonville to Route 89. Coal Mining In the early 1900s, a small coal mine opened about two miles from here, where local residents could buy hand-dug coal for their stoves. During the 1940’s, the Shakespear mine near Tropic used dynamite to blast the coal seams, and miners hauled out the coal with horse-drawn trailers.

Where it stands

Worth the stop nearby

• Cannonville — 1.9 mi
  Gateway to Kodachrome Basin and the Grand Staircase
• Henrieville — 2.2 mi
  A blink-and-you-will-miss-it ranching hamlet
• Kodachrome Basin State Park — 4.4 mi
  A valley of 67 stone chimneys rising from the desert floor
• Tropic — 5.1 mi
  A quiet pioneer town in the shadow of Bryce Canyon

More markers nearby

• Ebenezer Bryce Cabin — 5.3 mi
• Veterans Memorial Park — 5.4 mi
• Tropic Pioneers — 5.5 mi
• Paria Cemetery — 22 mi