The esker begins near the intersection of Main Street and Pitt Street. It continues to the southwest near County Road S 100 E. See waypoints for details.
An esker, which is a prominent ridge of sand and gravel, rises above the glacial landscape at the southwestern edge of Franklin. It extends about 3 miles to the southwest, where it flattens to an apron of sand and gravel. This ridge probably began as a tunnel that ran through the Wisconsinan ice sheet after the ice stopped moving. Meltwater flowing through the tunnel deposited sand and gravel that remained as a winding ridge after the ice melted away.
Another esker, east of Greenwood, stretches 8 miles. Still others once existed in Indianapolis but were mined for sand and gravel. This is a common fate of urban eskers.
The Franklin esker heads southwestward to the inner border of the moraine. At its southwest end it expands into a fan-shaped plain or delta covering about one-fourth of a square mile. This delta is a swampy depression 100 yards or more in width that separates it from the moraine. The esker itself has its head in a swampy tract which extends 2 or 3 miles farther north than the esker. It seems to have been formed by subglacial drainage in connection with it. A few gravel knolls and low ridges 4-6 feet high in this trough are referable to the stream which formed the esker.
The remarkable feature of this esker is its breadth, which in some places exceeds 1/8 mile, though its height is only 15 or 20 feet above border tracts. It may, however, have been formed in a very broad tunnel in or beneath the ice sheet.
To log this earthcache, send the answers to the following questions to my account.
1. Why do you think the road follows the path of the esker?
2. The elevation in the field below is 734 feet. Walk to the top of the esker on Windstar Boulevard and take an elevation reading. What is the difference in height from the field to the top of the esker?
3. Post a picture of yourself (face not required) or a personal item at the esker.
Esker on Mars!
Planetary scientists have discovered a rare ‘esker’ on Mars – a ridge of sediment deposited by meltwater flowing beneath a glacier in the relatively recent past (about 110 million years ago), despite cold climates.
With average temperatures on Mars of -55°C, it is widely thought that glaciers in the mid-latitudes – between the equator and the poles – are too cold to have produced meltwater. However, new research by the Open University (OU), in collaboration with University College Dublin, the University of Cambridge, and the University of Nantes*, suggests that, due to underground volcanic activity and heat generated by ice movements, the temperature beneath this specific mid-latitude glacier did rise enough to cause the ice to melt.
This meltwater then formed a tunnel, which filled with sediment and was left behind as a ridge, known as an esker, as the glacier retreated.