Wednesday, January 25, 2023

The Shoofly Oolites - A Geologic Wonderland in the Owyhee Canyonlands!

The author poses for a pic at the Shoofly Oolites. (courtesy Steve Schaps)

Guest Column
By Steve Schaps

The Shoofly Oolites are a geologic wonderland located about 60 miles southeast from Boise near Grand View, Idaho, at the foot of the Owyhee Canyonlands.

This location is probably the closest you can come to hiking on the surface of Mars. The hike is 1-3 miles in length. 

It is both dog friendly and kid friendly, so you can bring either one or both. This is a great place to bring kids or grandchildren. It’s about an hour’s drive from Boise, and a far less snowy or icy drive than if you were heading to the mountains to the north.

One of the main reasons to visit the Shoofly Oolites is the educational opportunity for kids and adults to learn about this geologic wonderland.

Oolites, known as “Egg Rocks,” are rocks made up of small round calcium carbonate deposits (not sand), which look like tiny BB-sized eggs. The Shoofly Oolites are one of the largest outcrops of Oolites in North America and possibly the largest freshwater Oolite accumulations on earth.

These Oolites were deposited in beach/shoal environments along the sides of ancient Lake Idaho around 2-5 million years ago in the Pliocene Era. Lake Idaho was in a large closed basin like the Great Salt Lake is today. It stretched from Eastern Oregon across most of the Snake River Plain, from Boise to the foothills of the Owyhee Mountains.

Most of the Treasure Valley’s groundwater and farm fields are in Lake Idaho deposits. It’s one of the reasons that the area has such abundant groundwater and agricultural resources.

Courtesy Steve Schaps 

The Shoofly Oolites are unusually thick, very homogeneous, and create an interesting area for a hike and geologic field trip. You can take home a few pieces of Oolite rocks, if you like. Bring a big. They are a bit crumbly.

The Oolite road-side stop is managed by the Bureau of Land Management. It includes a few educational interpretive signs and a parking area.

There are lots of weird and interesting rock formations to see. The kids love this part … there are all kinds of caves, holes, arches and bathtub features to explore. A game of hide and seek, anyone?   

The Idaho Museum of Mining and Geology will be leading a geologic field trip to the Shoofly Oolites on April 16. Go to for more information.

There’s also a historic cemetery located one-half mile up the road that you can also explore.

How to get there:

·      Take I-84 east toward Mountain Home

·      Go right at Exit 74, Simco Road.

·      Follow Simco Road south for about 20 miles.

·      Turn right on Idaho Highway 167 and follow that to Grand View. Stock up on gas or any supplies at the Grand View quick stop.

·      Go left on Highway 78 and go east for about 2 miles to a Y-junction.

·      Veer right on Mud Flat Road, the Owyhee Backcountry Byway, a paved road to begin with, and follow that for about 9.5 miles. The Oolite BLM site is on the right. GPS coordinates are 42.837128/-116.121980.

Courtesy Steve Schaps 

Steve Schaps has a bachelor's and master's degree in Geoscience. He worked for over 30 years as a geophysicist in Houston, Texas. He's retired now. He's lived in Idaho for six years. Steve is also a volunteer at the Idaho Museum of Mining and Geology. 

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