Welcome to the Columbia River National Wildlife Refuge, home of the Columbia Basin Basalt Towers.
Please note that access to the area where this earthcache is located at is seasonal. The access gates are locked from October 1 thru March 1. You will not be able to access this earthcache during that time frame.
Lets learn about the amazing geology of the Columbia River Basin.
About 17million years ago through about 6 million years ago, lava started flowing into this area. It is estimated there was about 300 individual lava flow outbreaks during that period of time. At first thought, the lava had come from the Cascade Range's volcanic peaks. After further study, it was determined that the lava that flowed into the area was of a different chemical make up and did not from the Cascade Range volcanoes, but rather from fissures in the earth's crust to the east. The lava flows from the fissures were MASSIVE. The flows were similar to the lava flows in Hawaii but by comparison in size the Columbia Basin lava flows cover a much great area than Hawaii. To understand the sheer size of the Columbia River Basalt Group, the lava that makes the basalt group covered most of eastern Washington from east of the Cascade Range and roughly south following a line from the Spokane River, Lake Roosevelt , and the Columbia River from Grand Coulee Dam until the river bends at Pateros and flowed south and then west into the Willamette Valley in Oregon and then continued west to the Pacific Ocean. See the map below.
The lava was at least a mile thick and is up to 3 miles thick in the central and lower Yakima Valley. The coverage area of the of the Columbia River Basalt Group is estimated to be about 60,000 square miles. The lava flows that became the Columbia River Basalt Group easily eclipses what is happening on the big island in Hawaii!
So now you know how these rock pillars got here, but why are they exposed? Great question! Its estimated that several times between 17,000 and 15,000 years ago, the great ice age floods swept through most of eastern Washington when the Ice dam that formed glacial Lake Missoula, gave away sending massive torrents of water into eastern and central Washington, sweeping carving out bedrock and sweeping away any sand or silt, exposing the basalt columns you see before you.
Now that you know how the basalt came to be and how it was exposed, let move on to the earthcache questions. Do not put your answers in your found it log, rather message me via geocaching.com with the answers to the following questions:
Waypoint 1 (listed coordinates): Standing on that large chunk of basalt lying on the ground, stand facing the columns and answer the following questions:
1) About how many individual columns can you see at this waypoint?
2) Describe the columns. Do they have smooth edges or jagged? Explain why your answer.
After you have answered these two questions, proceed up hill and get on top of the basalt columns where waypoint two is and answer the following questions:
Waypoint 2
3) Standing at the waypoint, describe the top of the columns. Would you say that the tops of the basalt columns are wildly random OR do they tend to conform to a specific pattern that is somewhat uniformed? Does this pattern remind you of other natural patterns that you have seen in nature? Explain your answer.
4) Looking down from the top of the columns, how tall do you think the basalt columns are?
Now head over to waypoint 3 for your final question.
Waypoint 3
Looking north you see another spectacular wall of exposed basalt columns. Take a good look at the columns and answer the following questions"
5) How long would you estimate the wall of basalt columns before you?
6) Are the basalt columns you see to the north about the same height as where you are standing? Are they higher or lower in elevation?
Once you have finished your observations, please message me your answers to the questions and then log your find. Again, DO NOT put the answers in your logs. Feel free to take pictures, just do not upload any spoiler pictures that might help with the answers to the questions.
Thank you for visiting this truly amazing area of central Washington. Keep in mind that this is a national wildlife refuge. You are a "guest" in this area. Respect the environment, practice "leave no trace". Again, thank you for visiting the area.
Acknowledgements:
Special "thank you" to Prof. Nick Zentner (Geology Professor at CWU) and Tom Foster for not only their inspiration for this earthcache, but generous use of their graphics and the info on their "Huge Floods" website.