Climbing Shoofly Oolite

“I don’t want to hike!” Hunter complained, a response Jessica and I anticipated (“He’ll say he doesn’t want to go but then have a blast when we get there”).

To be honest, I was concerned about this one myself. I’d hiked a bit^¹ around BLM’s interpretive site south of Grand View, Idaho, but wasn’t positive it would hold the kids’ interest long enough to justify the drive.

“Who can tell me what a fossil is,” I asked the back seat to help pass miles that seemed motionless.

Hunter loves to collect facts. He had the answer right away.

“We’re about to go by something that’s the largest in America,” I offered for the next challenge. “See if you can figure out what it is.”

“The river,” one guessed. The Snake was just coming into view.

“Nope.”

“Cow poop,” Hunter guessed.

“Close.”

In a moment we could see and smell the answer, Simplot’s Grand View cattle feedlot.^²

1. Trail Image, “Alone in the Owyhees”: trailimage.com/alone-in-the-owyhees; also Trail Image, “Zeno Falls on Ben”: trailimage.com/zeno-falls-on-ben
2. Institute for Livestock and the Environment, “Simplot Feed Lot”: livestockandenvironment.org/livestockandenvironment

After the typical, exponential progression of “are we there yet” inquiries along the largely linear route,^¹ I was pleased to tell the kids we were stopping at a cemetery. The small wire fenced space, barely noticeable from the road, forty feet away, seemed half-empty compared to what I remembered. A local lady we encountered later explained headstones have been removed to be refurbished or refashioned. Only a few remained.

The crumbling stone house in view of the cemetery was a way station and stage stop, the Turmes Ranch, established about 1880. Most interred at the cemetery are Turmes.

1. Google map: goo.gl/…/AcfEk

Interpretive signs at the trailhead, just up the road from the cemetery at a squat sign declaring “Shoofly Oolite,” explain the significance of the colorless hill ahead.

We advanced along the bottom of ancient Lake Idaho toward the hill, once a shoreline. What Pliocene creatures would glide overhead or ply the murky depths at our feet? Layer upon layer of sand, ash and silt, thousands of feet thick in places, are all that remain of a lake some two hundred miles long and thirty-five miles across that stood for countless millennia.^¹

0. starBureau of Land Management information panel, “The Big Picture”: blm.gov/…/ShooflyOolite_web
1. Bureau of Land Management, “Lake Idaho”: blm.gov/…/lake_idaho

“I found fossil bones!” Brenna exclaimed. There was no need to spoil her fun with the fact these were recent rodent bones.

“The Shoofly Oolite is one of the largest freshwater lake bed oolites known in the world.”^¹ Hunter’s pessimism was allayed when he saw the ooids. “Mom, look at this!” he called.

I was struck the first time I saw it too. What looks like regular sand from a short distance is a billion BBs up close — perfect little spheres of calcium carbonate encrusted sand grains piled deep, spread everywhere and cemented into stone called “oolite.”

0. starBureau of Land Management information panel, “Shoofly Oolite”: blm.gov/…/ShooflyOolite_web; also Wikipedia, “Oolite”: en.wikipedia.org/…/Oolite

I know it’s an okay hike when Jessica starts climbing the rocks.

Eroding sandstone and oolite has created the whimsical mansions of upper class birds and rodents.

Scattered, dark brown stones made me think of Boise’s foothills trails in the spring when everyone is out with their big dogs. Happily, these were just rocks. I thought they might be bits of volcanic splatter that hit the water every few thousand years, some of the evidence to “demonstrate the eruption of large volcanoes within standing water of the lake.”^¹

A study of the stratigraphy at that location mentions another option, “iron oxide concretions”^² in a layer between sand and oolite. I’m not sure what those look like. The paper doesn’t elaborate. I’ll say the brown rocks were heavy and solid like iron.

1. Shervais, John W., Gaurav Shroff, et al., “Tectonic and Magmatic Evolution of the Snake River Plain Volcanic Province,” p. 354: idwr.idaho.gov/WaterInformation/Projects/eada/publication...
2. Swirydczuk, Krystyna; Larson and Smith, “Volcanic Ash Stratigraphy of the Glenns Ferry and and Chalk Hills Formation,” p. 19, fig. 6: idahogeology.org/…/TR-81-1

A foot-wide tunnel cut straight into the sandstone a dozen feet until it bent out of sight was a curiosity. I noticed it was roofed by a layer of the dense, dark stones. Some geology work? Natural? It didn’t seem right to send the kids in without a flashlight so we may never know.

Above the oolite in the old lake shallows was a shelf of undulating rock we called Whoville. Like our first visit to Jordan Craters,^¹ it was fun exploring the many fanciful nooks and crannies.

1. Trail Image, “Snow on Coffee Lava”: trailimage.com/snow-on-coffee-lava

The physical and chemical properties of the Shoofly Oolite provide the foundation for the unique set of plants and fossils found here. Few other lands in Idaho support such a rich suite of rare species in such a small area.^¹

1. Bureau of Land Management information panel, “Shoofly Oolite”: blm.gov/…/ShooflyOolite_web

The kids called the eroded hollows “pop-outs” not for what they were, I was told, but for what you could do with them.

0. starI digitally removed a mom and two colorfully clothed kids from the middle background

A sunny hike through the Pliocene is not a bad way to spend a mid-November day. From being upset he had to go, Hunter went to being upset we didn’t have time to play on every last outcrop. But we expected that. Nature draws us in, young and old, and we forget to fret.