Esker and Kame Formation
A moraine is formed by glacial debris (soil, rock, sand) accumulating in current or former glaciated regions. Obviously this area is the latter and we will be dealing with two types of moraines; eskers and kames.
An esker resembles a long, narrow, winding, steep-sided ridge of irregularly layered gravel and sand. In fact, the word “esker” is Irish for ridge. Eskers can form when a stream runs under, on top or at the edge of a glacier and deposits material as it flows. As a glacier recedes, these deposits are left behind. The biggest esker near the paddock is almost 18 metres high, between 10 and 60 metres wide and over three kilometres long. While driving on the loop road, once you get out to the farthest point and start to come back (ES waypoint), you are actually driving on top of an esker.
Eskers left by streams at the bottom of glaciers are called subglacial eskers. These eskers tend to be continuous ridges with a consistent, unbroken form and stratified layers of sediment. When the stream ran on top or through the glacier, rather than beneath it, the sediments become disrupted as the glacier melts and retreats. The eskers that result are known as supraglacial or englacial eskers. Their form is more broken, and the sediments are not as neatly stratified.
Kames can be composed of the same materials as eskers but instead of forming as a ridge, they are hills. There are also three places a kame will form; in a delta from a stream at the base of the ice, in a hole on top of the ice where a stream flows down or as a pond on the surface or at the edge of a glacier. The Bison Overlook is actually situated on top of a rather large kame.
As this is the home of a herd of bison, you may see them from the overlook or as you drive around the paddock. Near the end of the loop, before you drive downhill off the esker (BV waypoint), you should see an area without grass (just dirt or mud) to the west. This is a common spot for the bison to wallow (roll in the dirt) to get relief from biting insects and to remove tufts of molted fur. During the rut (~July to ~September), males will also wallow as a show of strength and virility.
In order to log this EarthCache, please send me an email (through my geocaching profile, kindly do not post in your log) the answers to the following questions:
On the first line of the email, please include the text “GC3XH9A – Eskers, Kames and Bison”
1. Looking at the largest esker to the west, in which direction is it oriented (ie. north to south)
2. Seeing the formation of the eskers, would you say they are subglacial, englacial or supraglacial?
3. For the kame under foot at GZ, would you say it is of subglacial (under) or supraglacial (on top) formation?
4. Knowing the composition of the eskers and kames, why would they not make a good spot for bison to wallow?
5. Photos at the cache site are always appreciated but no longer a requirement to log an EarthCache.
There is no need to wait for me to respond, please submit your answers and log at the same time. Posted logs that do not have the associated answers emailed within seven (7) days will be deleted. Please feel free to re-post once the answers have been sent.
Remember, there is no physical container to be found for an EarthCache site.
References:
1. A Traveller's Guide to Geological Wonders in Alberta by Ron Mussieux and Marilyn Nelson
2. Rocks, Ice & Water, The Geology of Waterton-Glacier Park by David D. Alt and Donald W. Hyndman
3. Parks Canada correspondence
3. Grasslands Esker http://coord.info/GC1PQT1
4. LSGA Kame Field http://coord.info/GC239AW
5. Eskers Park EarthCache http://coord.info/GC4MV0Q
6. Wikipedia – Esker http://en.wikipedia.org/wiki/Esker
7. Wikipedia – Kame http://en.wikipedia.org/wiki/Kame
8. [US] National Parks Service http://www.nps.gov/yell/learn/nature/bisonfaq.htm
