Sunday, March 1, 2009

Ice-Rafted Erratics in Jackknife Canyon

This huge granite boulder was floated to this location aboard an iceberg during one of the Ice Age Flood events that swept over eastern Washington near the end of the most recent Ice Age.

In late February I visited two of these large erratics above Jackknife Creek after hiking north from the Rocky Coulee parking area near the Gingko Petrified Forest State Park visitor center. Later in the year it may be easier to access the Jackknife Creek area via the green dot road system for those that don't mind a bumpy ride using high clearance vehicles, motorcycles or perhaps a rental car.

After crossing the State Park, I entered the Whiskey Dick Unit of the L.T. Murray Wildlife Area. This is wide open country with both erosional and depositional Ice Age Floods features to explore. If you head out here to visit the big erratics make sure to pack a lunch. The hike ended up covering 20.7 miles.

The largest of the Jackknife Creek erratics is visible from Frenchman Coulee. When visiting Frenchman Coulee, take a few minutes to explore the west side of the river with your binoculars. The floods really did a job on the basalt over there.

From Bruce Bjornstad's book:
On the Trail of the Ice Age Floods

"Of special interest is a high, sculpted-out area in the steep wall of basalt visible on the opposite side of the Columbia River from Frenchman Coulee. Like a giant fire hose, a forceful jet of floodwater hit this rock wall head on after cascading through Frenchman Coulee."

As soon as you start hiking across the State Park land you'll see plenty of ice-rafted erratics scattered over the landscape. This part of the state has been covered by dark brown Columbia River Basalt so granitic boulders are often visible from great distances.

The flood sculpted terrain along with the material deposited by the floods are enough to get me out here. Viewing the petrified wood is a bonus.

Hard to select just a couple petrified wood shots to post. I took quite a few during the hike.

So much petrified wood out here that the guys setting this benchmark in 1957 pressed some into the concrete.

Petrified Log

I sure enjoyed the view as I walked north high above the Columbia River. Locations marked on photo are: 1. Sunland, 2. Babcock Bench, 3. Frenchman Coulee, 4. Interstate 90. Click any of the photos to enlarge.

Degree Confluence

A destination for some is out there on the surface of the Columbia River: 47°N 120°W

I'm not sure what I was thinking when I decided to cross the Hole In The Wall drainage rather than walk around the west end. It sure ate up the time and I didn't find much of interest down there other than a small cave.

As I was trying to work my way down to the river I saw this guy to my right. He was looking down the river and didn't realize that I was behind him. As soon as my camera clicked he gave me this profile view and then took off.

Wish I could have spent more time at:

N 47°00.411'

W 120°00.482'

Some nice basalt exposures in all directions.

Walking on top of the columns.

Moss covered petrified log.

Leaving the hike for a minute here. Wanted to mention that I visited the Yakima Museum's new Miocene Forest exhibit a couple weeks ago. The museum page notes that geologist Nick Zentner (Ellensburg IAFI chapter President) was one of the experts consulted in the development of the exhibit. The display is beautiful and helps tell the story of the forest that existed here 15 million years ago.

The museum's Time Tunnel exhibit provides information relating to the Columbia River Basalt Group, the Ice Age Floods and some of the animals that once inhabited the area.

Antlers near Cayuse Creek

Many deer (like the one that wore these) use the Whiskey Dick Unit but the animal the area is known for is the Rocky Mountain elk.


This area is important winter and early spring habitat to some of the 4,500 animals that make up the Colockum Elk Herd. The link opens a 58 page document that describes the herd including a description of the strategy used by WDFW to manage their population on the West Bar (Giant current ripples).

The WDFW herd history states that the main Colockum herd developed from 45 Montana Rocky Mountain elk released near Boylston and driven north at Vantage in 1915 (Pautzke, 1939). Zooarchaeological data from the Columbia Basin suggest elk were present and utilized by early inhabitants (McCorquodale 1985, Dixon et al. 1996). By the late-1800s elk may have been extirpated from the Region (McCorquodale 1985). The current Colockum elk population
developed from the reintroduction of Rocky Mountain elk (Cervus elaphus nelsoni) from
Yellowstone National Park in 1913 and 1915, which significantly contributed to any remnant animals in the area (Bryant and Maser 1982).

Frenchman Coulee

These small current ripple marks in the sand caught my eye along the Columbia River (note footprints for scale). They reminded me of ripple marks on a much larger scale created a few miles to the north by the Ice Age Floods.

This photo of the giant current ripples on West Bar was taken just before sunset in June. Some of the West Bar ripples are 24 feet in height and 360 feet apart. Geologist believe the water that created these ripples was 650 feet deep!

I like seeing the suitcase size erratics but I was anxious to see the large one I'd spotted from Frenchman Coulee.

Cluster of small erratics, Frenchman Coulee in the distance.

The smaller of the two large erratics above Jackknife Creek. Note: Columbia River in the distance.

Another view of the erratic shown in the previous photo. Arrow identifies the large erratic I viewed from Frenchman Coulee.

Hard to believe this 9' tall rock floated into Kittitas County.

Could be the top of a 30 footer?

Many sections of the green dot roads near the river are cut into flood deposits.

Area Roads Closed Until May 1st

A closure to motorized vehicle access on the Whiskey Dick and a portion of the Quilomene wildlife areas in Kittitas County is in effect from February 1 through April 30 during 2008 and 2009 to protect wintering elk. The area is north of the Vantage Highway, south of Quilomene Ridge Road, east of the Wild Horse Wind Farm, and west of the Columbia River. The effectiveness of the closure will be evaluated at the end of that period to determine whether it should become permanent.

Anyone know what kind of bird this is?

Tom Email

On my way back to the car I spent some time looking at Sentinel Gap. This restriction probably had a lot to do with the location of many erratics in the Ginkgo area.

The movie below is VERY low quality but it does show views of the large erratics above Jackknife Creek:

Links to December 2008 hikes at Ginkgo Petrified Forest State Park:
Ginkgo State Park Part I

Ginkgo State Park Part II


Anonymous said...

This is your best post yet, Tom. I've always meant to hike north from the Ginkgo Museum along the river. This inspires me to get out there soon. The shots of the Frenchman flood deposits from across the river were especially interesting. You're the man!

Nick Z

Anonymous said...

Nice work Tom, this is great stuff. I get excited just looking at some of these photos. I look forward to exploring some of this terrain north of the park. But may need to buy some boots!

Ryan K