A glacier is a persistent body of dense ice that is constantly moving. It is formed when winter snowfall exceeds melting in the summer. Glacial ice is the largest reservoir of freshwater on earth. Glacial mass changes are considered to be the most sensitive indicators of climate change and are major source of variations in sea levels. Projected glacier demise is severe as it is estimated that 80-90% of glacial volume will be lost by the end of this century. As glaciers melt and thus recede they leave behind glacial till (mixture of rock, gravel, sand and clay). The great weight of the moving glaciers grind and polish the rocks and rock beds below. The polishing is done in two ways: 1. direct abrasive action of the ice flow, 2. by sand and other small particles embedded within the ice like sandpaper. The glaciers also plucks out rocks from the rock beds and deposit them elsewhere. The melt water forming the streams and proglacial lakes (lakes formed along the edge of melting glaciers) often acquire a milky colour from the "rock flour" or "glacial flour" which consists of fine-grained, silt-sized particles of rock, generated by mechanical grinding of bedrock by glacial erosion. Because the material is very small, it becomes suspended in meltwater making the water appear cloudy, which is sometimes known as glacial milk. It is usually not just a simple clay but for the most part specifically quartz and feldspar particles. You will find yourself hiking along the Snowbird Pass Trail when you arrive at Ground Zero (GZ) where you will witness evidence of past Robson Glacial activity as it receded. Beside you is the rushing creek - meltwater originating from the Robson proglacial lake with the characteristic milky colour. If you hike another mile or so along the Snowbird Trail you will see this proglacial lake (unofficially known as the Robson Lake) at the edge of the Robson Glacier. Along the trail on the left you will see polished rocks and lines ground into them by pebbles trapped under the past flowing glacier. From the distance, you will appreciate huge rock and particulate load of the Robson Glacier forming bands giving it a dirty appearance.
To log this cache you must get to the coordinates in person. There you will find an informative plaque You must email me answers to the following questions (not post in your log):
1. At what rate does the Robson Glacier recede?
2. Who originally marked the toe of Robson Glacier in this location?
3. In what year was the Robson Glacier toe marked in this location?
4. Optional: any photos from the area (not of the plaque).
After completing this Geo-Earth cache please consider completing the hike to the Snowbird Pass. Most hikers become mesmerized by the Berg Lake and Berg Glacier's magnificence and probably go no further and thereby miss out on the Snowbird Pass which is probably even more fascinating.
Before your trip obtain a backcountry camping permit at the Visitor Centre on Highway 16 by calling Discover camping at 1-800-689-9025. By vehicle you may wish to travel from Jasper townsite west 84 km on Yellowhead Highway 16. From British Columbia side you will travel 16 km east from Tete Jaune Cache junction. Stop at Mt. Robson visitor centre on the north side of highway and register there. There is a restaurant, information centre, ranger station and a gas station. Then from there you can follow the trailhead access road north for about 2 km with ample free overnight parking. Greyhound busses also make runs east and west on Hwy 16. The trail is well maintained with many bubbling creeks crossing you path. I did not filter the water from these as I drank it but it is generally recommended. The glacier silt in the water tends to plug up filters anyways. As you hike along I would recommend filling a bottle right at the suspended bridge over Robson River as there is no water over 4 km thereafter on the ascending switchbacks where your cardiovascular system will be tested and you will be dripping with sweat.
Best time to go is in July-August, unless you are an experienced alpine backcountry skier. No campfires are allowed in this highly protected ecosystem so bring a stove. Needless to say that this is a Grizzly Bear country and there are other inherent risks involved in this fine Canadian wilderness. It is not for the weak or faint at heart.