Here is a quick easy EarthCache, to boost your numbers, earn a souvenir for the month of August and learn a little bit about the geology of the Walla Walla valley.
When approaching this EarthCache, you will need to exit Hwy 12 to the East onto Lewis Peak Rd. Once you've exited, find a safe spot to turn around and park just before the stop sign on the corner. The small grain elevator on your immediate right has been built into a private residence, so please do not block or park in the driveway. There is plenty of room to pull up in the county right-of-way just before the stop sign. This should only take a few seconds to complete and you can be on your way. Check carefully for traffic before reentering the highway. WWPC can not be held liable because you failed to look for cars while at a stop sign and pulled in front of someone. Just look, you can see traffic a long ways off in both directions. Now that's out of the way, let's get to the good stuff!
Loess: a clastic, predominantly silt-sized sediment, which is formed by the accumulation of wind-blown dust. (Wikipedia)
At your stopping point, you can see in front of you on the highway cut, across the highway, DIRT!!!
But, not just any dirt. A Loess. A thick Quaternary Loess even! Why is this so interesting you ask? Well let me tell you. When basalt flows covered this area, a really, really long time ago (around 17,000,000 years) the area was covered with, well, basalt. Where did all this rich, fertile soil come from you ask? Wait for it, floods and wind. Yep, you heard it here.
Glaciers stretching down from Canada formed ice dams in North Eastern Washington, Northern Idaho and North Western Montana. Behind the glacial dams, Lake Missoula was formed. At the ice dam, the water was approximately 600m deep, roughly 2000 feet. This all occurred between 13,000 to 15,000 years ago. Well, that gigantic ice dam failed, many, many, many times. Each time the damn failed, our little valley would have looked like an inland sea. Hundreds of feet deep! As the water receded, silt and sediment were left behind. Over and over and over again. Cool huh!
Now for the other part, the wind! About 6845 years ago, a large volcano erupted in SW Oregon, Mt. Mazama. This eruption formed, wait for it, isn't science great, Crater Lake! The heavier materials (rock and pumis) were deposited nearer the volcano, but the lighter ash and silts were carried by, you guessed it, the wind! Much of these materials were deposited right here. Adding to our rich, fertile soils.
So, what's so special about this little stop we've brought you to? On the cut, across the highway, you can see the evidence of these deposits. There are two destinct deposits, one sloping South and one sloping North. Another tidbit about this spot, every drop of rain that falls here runs either North to the Touchet River or South to the Walla Walla River. If you look closely you can see that the deposits are two distinct colors and are stacked. Do to erosion, the lower deposit, is partially covered and a little harder to see, but the top of it is visible. The upper deposit is almost completely exposed. I recommend not doing this cache in the late afternoon, the sun will be directly in your eyes and makes peering through your windshield a little tough.
To log this cache, email us your best estimation of the thickness of the upper deposit in feet. Include in your email the time of day and the suns position and how easy it was to see the deposits.
For bonus points, travel South toward Dixie and about 1/4 mile from Lewis Peak Rd., you can clearly see the exposed basalt that is millions of years old! If you travel North towards Waitsburg, you can clearly see the lighter ribbon of soil running along beside you, parallel to the highway!
Thanks for stopping and we hope you've enjoyed this little bit of our geologic history.