Historic Kansas attraction recovering from last year’s rare landslide
Heavy rains were blamed for a rare landslide last year that made access unstable to Coronado Heights Park, near Lindsborg. (Submitted by Neil Croxton to Kansas Reflector)
As a historic Kansas landmark neared its centennial last year, heavy summer rains loosened several layers of earth and triggered a rare three-foot slump in the landscape.
Damage at Coronado Heights Park, which sits on a 300-foot sandstone bluff northwest of Lindsborg, made access unstable. The landslide forced cancellation of a 100th anniversary party planned for June of 2019, as well as ongoing repairs and attention to drainage issues.
Heavier than average rainfall on the weekend of the planned celebration, as well as weeks prior, led to a break in the sites underlying rock and clay.
“It was the most displacement I’ve seen in Kansas all at once,” said Neil Croxton, a geologist for the Kansas Department of Transportation. “A three-foot drop, cutting a road, is unusual in Kansas because few roads climb as steep a feature such as this one.”
Croxton said it is because the Smoky Hills Buttes, which includes Coronado Heights, are capped by a specific type of sandstone that has prevented the underlying clay from eroding completely.
“This clay material was never buried deeply enough to turn into rock shale,” Croxton said. “It is really just stiff clay. And at Coronado, that clay is on a steep slope under the sandstone.”
According to Croxton, the layered sandstone and clay is already low strength on a good day, but after multiple weeks of rain last spring, two things happened.
“The rainwater added a lot of weight to the surface layers, and it also soaked into the clay itself and weakened it further,” Croxton said. “Eventually there was a break.”
When that break occurred, those rain-soaked layers dropped by three feet, cracking the road up to the park. The road was fixed in the months following the land drop, and the Smoky Valley Historical Association has received a small grant to pay for continued road maintenance. Tim Stewart, president of the nonprofit, said there are still issues with rain and drainage.
“There’s been a few times where water has run across the road, creating little trenches, so we go back over it and smooth it out,” Stewart said. “As soon as rain hits, we have to go up and investigate, see what needs to be done.”
Coronado heights, legend has it, is where the explorer Francisco Vásquez de Coronado abandoned his search for the seven cities of gold and decided to return to Mexico. The drainage system for the park was built in 1935 as part of a scenic overlook project by the federal Works Progress Administration.
Stewart said his organization replaced one drain shortly after the land drop, but there are still two more that need to be dug up and replaced.
“That’s the key to maintaining the road going up there,” Stewart said. “We get the drainage correct to where it’s not damaging the road every time we get a huge rain, and it’ll be more absolute in the fact that it lasts longer.”
Much of central and eastern Kansas recorded greater than average rainfall during the spring and summer months of 2019. Roger Martin, meteorologist for the National Weather Service office in Wichita, said those months saw “anomalous moisture at times.”
“With thunderstorms, sometimes you can have all the ingredients for heavy rain but not always get it,” Martin said. “In the case of 2019, the ingredients were regularly there for heavy rain, and we regularly had storm systems to take advantage of those ingredients.”
Martin said rainfall for east-central Kansas was 150% above normal from March to August of 2019. By comparison, those same months for 2020 have been noticeably dryer.
Landslides aren’t uncommon during wetter years in Kansas. Croxton said most of these events happen away from roads and buildings, so they are not noticed. He said it is difficult to mitigate landslide activity simply because each occurrence is different and needs to be looked at individually.
A plan is in effect for the remainder of the year to continue improvements to the road and drainage network at Coronado Heights. Stewart said the Smoky Valley Historical Association is working with two central Kansas construction firms to resurface the road and continue general maintenance.
The organization has raised more than $90,000 to fund its second phase of repairs, which included the replacement of the original storm drains with much larger ones. The first phase was completed in 2016 and involved separate improvements to the stone castle and entrances. Stewart said the organization was fundraising for the second phase when the land drop happened, and he is hopeful for a sunnier future.
“We will continue to add rock, not only on the road but on the very top, as well,” Stewart said. “Hopefully when the COVID-19 pandemic goes away, we can get back to doing more public things. … Maybe we will eventually have our 100th anniversary program.”
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