Important things to know to avoid log deletion:
- if your answers will be sent at a later time, state when I will receive them in your found log.
- required photo must be personalized in some way so that I know you were truly there.
If I delete your found log due to lack of following instructions, you can re-log your find when you are able to comply.
Additional information before you start to keep your found log in place:
- Parks Manager Kerry Hibdon requests that you do not remove rocks from this site.
- each cacher is required to post a photo in their found log of herself/himself (or identifying object) at the stated location, so remember to bring a camera or phone.
- read the cache page text to help you answer the questions. If you use this information in addition to what you see, it will be obvious that you have made a sincere effort. (If additional information is needed clarify things, I will work with you after receiving your answers.)
- include nothing related to the answers in your found log.
- if you are sending answers for others as well as yourself, state their caching names in the message with the answers.
- if someone else sent in your answers, state that and give their name(s) in your found log.
Things you'll need to complete this earthcache:
- willingness to read the cache page for understanding before sending in answers.
- measuring device in millimeters.
- a camera or phone to take the required photograph.
- advised - a walking stick will provide stability the last few hundred feet.
History and Park Information:
The upper Deschutes Falls Park, southeast of Rainier and Yelm, includes most of a nearly half-mile long series of waterfalls on the upper Deschutes River. These falls were part of private parks between the 1920s and the 1990s. Thurston County purchased the property in 1992 and opened the park to the public 25 years later in 2017.
The waterfall is the namesake of the 155 acre park. To see the main waterfall, go to the viewpoint for the nearby virtual cache. Deschutes Falls plummets into the Deschutes River below where banks rise over 70 feet. The river races through a 400-foot gorge and settles into a wide basin. Before the main falls, a series of smaller falls is visible from the waypoint for this earthcache. Downstream of the falls the river flows through an impressive nearly slot-like canyon for several hundred feet. Unfortunately there are no good views down into the canyon from the developed viewpoints along its rim. Hopefully that will change in the future.
Geological Background:
The waterfalls were formed by the Deschutes River cutting through ancient rock mudflows left behind by a long gone stratovolcano/mountain which no longer exists. In the millions of years since molten rock erupted and spread across what was then the coastal plain, forming the stratovolcano, it has eroded from the landscape. The underlying rock is still here, but an entire volcano, estimated to have rivaled the size of Mount Rainier, has simply disappeared over time. The rock through which the Deschutes River Falls are found is some of the oldest visible rock in Thurston County, dating back over 30 million years.
This volcanic rock formation lies across most of Lewis County and crosses into Thurston County. In Thurston County most of this layer of rock was covered by newer layers except for the portion now exposed by the Deschutes River. The ancient volcanic rock can be as deep as 1,400 feet and was laid down as long as 37 million years ago. It, and a series of other volcanoes, originated from when much of Western Washington was not yet above the ocean. In that era, anything west of Tenino was part of the Pacific Ocean and the rest of what we know as the Cascade Mountains formed a wide coastal plain.
About 40 million years ago volcanoes began erupting along this plain. They developed into the early parts of the Cascade Range, but not the range we now know. These early volcanoes spewed lava that created areas like this. They are now extinct and have been replaced by peaks such as Mt. Rainier and Mount St. Helens. They eroded away while the active portions of the Cascades we see today continued to grow.
Research by Paul Hammond of Portland State University shows that the “eruptive center” of the lava flow that formed the Deschutes Falls is somewhere near Newaukum Lake, about 9 miles north of Mossyrock.
Looking into and across the falls you will see the effects of this long-time erosion. Looking at the rocks nearby, you will be able to find evidence that lava once spewed out of a volcano in this area. One of the most recognizable things you can see here are the small rocks with vesicles. Vesicles are the very small holes or pores found in some of the local rocks. They are the result of gas expansion bubbles and the movement of these bubbles through the basaltic lava during volcanic eruptions.
Types of rock:
There are three types of rocks found in the world:
- igneous rocks are the "new kids" on the block. When heat is great enough to melt other types of rock, it becomes magma and either cools intrusively (inside the earth) into igneous rock such as granite, or cools extrusively (outside the earth) such as when it is spewed forth as lava during a volcanic eruption.
- sedimentary rocks are "recyclers," taking pieces of any other rock and turning it into a new one. This happens when other rocks break apart as a result of erosion, and are transported to lakes and oceans by rivers and streams. As the sediment piles up, compression and heat lithify it into sedimentary rock.
- metamorphic rocks are "change makers." When any type of rock is subjected to very high heat and pressure, the chemical and structural makeup of the minerals of the rock is altered, creating new, metamorpic, rock
Questions and tasks:
1. At the stated coordinates, across the water, you will see distinct, rounded indentations in the wall. Give a explanation of why erosion and water caused this indentation rather than leaving a straight wall of rock. Yes, the water is now swirling and enlarging them; however, why are they there - in other words, what caused the indentations to start?
2. Take your photo including an indentation in the background and post it with your found log. If you are camera shy, include something in your photo that will identify you as a geocacher.
3. Walk to the waypoint coordinates. In that area, find a rock with vesicles as described in the text. Vesicles will look like little indentations. Describe the rock you select - color, size of vesicles, and whether there are many or just a few vesicles in the rock. Remember, do not remove any of these rocks. There are many rocks with vesicles embedded in the hillside above the little trail.
4. Based on the rocks with vesicles, what type of rock mentioned in the above text are you finding here? Give reasons for your selection.
5. List the three types of rock listed in the above text in the order of how much heat it takes to produce them - from least amount of heat to most.
Sources:
- "The Geology of Thurston County's Upper Deschutes Falls" - Emmett O'Connell
- "Northwest Waterfall Survey" - www.waterfallsnorthwest.com/waterfall/Deschutes-Falls-5324
- "Washington Geology" - www.dnr.wa.gov/Publications/ger_washington_geology_1998_v26_no1.pdf#page=20