Please note - there is NO guaranteed cell phone reception at this cache site. Know the requirements for this earthcache before arriving.
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.
This entrance to Mount Rainier National Park is generally open from mid-June to mid-September. There is an entrance fee, good for 7 days, for each vehicle entering the entire park unless you have a special pass such as an annual pass or a Golden Eagle Pass. Information about these passes can be obtained at the entry points to the park. Please park only in designated parking spots and do not leave the trails/sidewalks during your explorations.
Equipment needed for this earthcache:
- binoculars may be helpful
- a copy of the text and the questions to be answered
Your answers are to be based on reading the cache page and what you see when visiting. No information will be on any of the reader boards.
Glaciers - they're just like nightmarish visitors to your home. They arrive at will and carry all sorts of baggage with them. While visiting, they tear up and devour things with no concern for your home or your well-being. When they depart, they leave massive amounts of evidence of their visit. Your home will never be the same - it has undergone permanent changes.
Yes, glaciers tear things up and move them around as they grow and constantly move. When they recede or disappear, they leave all sorts of evidence of having visited. Let's think about things they leave behind to help geologists track their visits.
1. Valley shape
The most obvious thing they leave are broad, U-shaped valleys. These valleys are carved out as the glaciers flow downslope, dragging debris with them for hundreds of thousands of years. It starts with just a scratch and wears into a broad U-shaped valley over time, rather than the narrow V-shaped valleys of rivers.
2. Moraines
Glaciers, as a result of both accumulation and ablation, create and leave behind four types of moraines, the masses of rocks and sediment carried and deposited by glaciers as they grow and/or recede.
- lateral moraines result as the sides of valley glaciers accumulate large quantities of debris from the valley walls. As the glacier wastes away, these materials are left as ridges, or lateral moraines, along the sides of the valley.
- medial moraines occur where two glaciers coalesce and moraines are formed at their junction. Moraines seen in the middle of valleys or as extensions of lateral moraines are indicators that at one point in time two glaciers met there.
- end moraines are ridges formed at the terminus/end of a glacier. These relatively common landforms are deposited when a state of equilibrium is attained between ablation/recession and accumulation/growth.
- ground moraines are till-covered areas with irregular topography and no ridges. They are accumulated at the base of the glacier as lodgement till* and may also be deposited as the glacier retreats. In alpine glaciers, ground moraines are often found between the two lateral moraines. As a glacier retreats, it creates a rock-strewn, undulating plain. It has a leveling effect, filling in low spots and clogging old stream channels. Poorly drained swampy lands are common in these areas.
*lodgement till: the unsorted glacial sediment located between a moving glacier and its bedrock bed that is laid down directly or reworked by a glacier. The material is often severely sheared, compressed, and over-compacted.
3. Outwash Plains and Valley Trains
> At the same time that an end moraine is forming, water from the melting glacier cascades over the till, sweeping some of it out in front of the growing ridge of unsorted debris. Meltwater generally emerges from the ice in rapidly moving streams that are often full of suspended material. As the water leaves the glacier, it moves onto the relatively flat surface in the area above the ground moraine and rapidly loses velocity. As a consequence, much of its load is dropped and the meltwater begins weaving a complex pattern of braided channels . In this way, a broad, ramp-like surface is built adjacent to the downstream edge of most end moraines. When the feature is formed in association with an ice sheet it is termed an outwash plain; when it is largely confined to a mountain valley it is usually referred to as a valley train.
4. Kettles
Kettles are commonly found at the location of end moraines, outwash plains and valley trains and are seen as basins or depressions. Kettles form when blocks of stagnant ice become wholly or partially buried in glacial outwash. They eventually melt, leaving behind pits in the glacial sediment. Most kettles do not exceed 1.25 miles in diameter and the typical depth is less than 30 feet. In many cases water eventually fills the depression and forms a pond or lake. Over time, most kettle holes fill with water, sediment or vegetation. As sediment accumulates in shallow kettles, they may become swamp land and eventually fill to the point that trees and other vegetation are all that will be seen.
How to claim a find for this earthcache:
To get credit for this earthcache, send the answers to the questions to me. Please log your find as soon as you send the answers - do not wait for my response. I will contact you promptly with approval or let you know if I need additional information from you. I may also send additional information to you if appropriate. If answers are not received in a timely manner, found logs will be deleted. Cut and paste the following into your response with the answers, preferably through the message center. (My responses to you will be sent through the message center.)
Cut, paste, and add the answers using both the text and your observations:
The Things Glaciers Leave Behind earthcache requirements and questions:
1: Be certain I know which earthcache For which are you sending answers? (if you click on the CO name on the cache page to go to the message center, this will be automatic)
2: Standing at the stated coordinates, what evidences to you see that a glacier once covered this area? Use the text above as a reference.
3: Do you see evidence of moraines? If so, which type? Text will be helpful.
4: Are you looking at an Outwash Plain or a Valley Train? Give the reasoning for your answer after reading the text. Incorrect answers makes it it obvious that the text wasn't read.
5: Do you think the kettle lakes below average 100 feet of depth? Why or why not?
6: Required to keep your "found" log in place - a photo of you or your name on a badge or piece of paper overlooking the view posted with your found log.
For those who enjoy hiking and want to get closer to things left behind by glaciers, coordinates for the Palisades trailhead with a map of the trail system are below. By taking the Palisades Trail you can hike 7 miles roundtrip and see 6 kettle lakes, including Tom, Dick and Harry, along the way. An additional side trail will take you to a 7th lake. The easiest lake to see from the cache coordinates is Sunrise Lake.
Sources:
Essentials of Geology, Lutgens, Tarbuck & Tasa
Roadside Geology of Washington, Alt and Hyndman.