Hogbacks

The cut beside this exit is a reference point for geologists. The Romeroville Sandstone, the upper unit of the Dakota Group, was formally named from its type section in the east-facing I-25 roadcut at Romeroville Gap, about five miles south of Las Vegas. Its hard, tilted beds make the ridges the panel calls hogbacks, and sandstones of the same Dakota Group hold the dinosaur tracks at Clayton Lake. The softer rock between the ridges wore down into the valley the wagons followed toward Glorieta.

What the plaque says

Official Scenic Historic Marker Hogbacks Interstate 25 cuts through dip- ping strata that form hogback ridges between the Great Plains and the south end of the Rocky Mountains. The Santa Fe Trail from here to Santa Fe, followed a natural valley eroded in less resistant strata between the mountains to the north and Glorieta Mesa to the south. Elevation 6,200 feet.

Where it stands

Worth the stop nearby

• Montezuma Castle — 9.3 mi
  The railroad's turreted resort at the Las Vegas hot springs, burned twice in its first years, empty for most of a century, and now home to an international school.
• Pecos National Historical Park — 25 mi
  The red walls of a 1717 mission church inside the foundations of a far larger one, beside the kiva Pecos people dug in front of the old church during the revolt of 1680.

More markers nearby

• Dr. Meta L. Christy — 5.7 mi
• Fabiola Cabeza de Baca Gilbert — 5.9 mi
• Las Vegas — 7.4 mi
• Villanueva State Park — 18 mi