Pennsylvania's Only Drumlins EarthCache

This EarthCache is located on state gamelands. Please abide by all gamelands rules when visting this site, and wear orange as appropriate. Some minor bushwhacking may be required between the first 3 stages, and you may need to cross a small stream depending on your approach.

You will visit two drumlins. The first is located in the woods and will require a bit of a hike. The posted coordinates, as well as stage 2 and 3, are a part of a single drumlin. Stage 4 takes you to the second drumlin more out in the open. You will make your observations at these locations. Parking coordinates are provided for the first drumlin. Parking is also available at stage 4.

To log this EarthCache, post your log here (please no answers to the questions in your log!) and send us a message through geocaching.com with answers to the questions below within three days:

1) As you walk from the posted coordinates to stage 2 (you will encounter vegetation, so a straight path will not be possible), look to your left and right. What do you notice about the terrain around you? Does it appear steeper near the posted coordinates or near stage 2?
2) Take elevation readings at the posted coordinates, stage 2, and stage 3. How do the readings compare?
3) What object do you see at stage 3 that is evidence of glacial activity?
4) At stage 4, look around in all directions. Walk along the gamelands road to the south, and feel free to cross Kimball Road to the other parking area as well. Describe what you see in terms of elevation changes in each direction.
5) Based on your observations at the two drumlins, in which direction did the glacier that formed these drumlins travel? Justify your conclusion based on your observations.
6) (Optional) Post a picture of yourself and/or a personal item while completing this EarthCache.

The term drumlin comes from the Irish term droimnin, meaning 'littlest ridge.' A drumlin is an elongated hill in the shape of an inverted spoon or half-buried egg that is formed by glacial action on underlying sediment. Drumlins often occur in groups referred to as fields or swarms. They can vary in length but are generally at least a quarter mile in length in the long direction. Drumlins are composed primarily of glacial till. They typically form near the edges of glacial systems and within areas of fast flow within ice sheets. They are often found with other glacial features, including eskers, scours, kettle lakes, bedrock erosion, and glacial erratics.

Drumlins can vary in size, and a drumlin's shape indicates the direction of motion of the glacier that formed it. As they resemble a half buried egg, they have a short axis and a long axis. The drumlin also has a steeper, blunt end and a less steep, more pointed end along the longer axis. The blunt end is typically the highest end, called the stoss side, with the drumlin tapering off towards the more pointed end, or the lee side. The diagram below illustrates this.
Image source: https://nsidc.org/cryosphere/glaciers/gallery/drumlins.html

Drumlins are believed to be formed via one of three processes. These are deposition, deformation, and erosion. In the depositional theory, it is believed that drumlins develop by repetitive addition (or accretion) of till around pre-existing accumulations of stratified drift or around a bedrock knoll. This could also occur via frost heave, whereby subglacial material freezes and expands, thus pushing material upward to form a mound-like landform. This then acts as an obstacle, around which drift material accumulates to form a drumlin.

In the deformational or till-squeeze theory, it is believed that voids or cavities beneath an ice sheet are filled with underlaying till material, and the material is further squeezed into hollows and shaped into drumlins by subsequent ice advance. A pressure differential is created, which forces subglacial material to zones of lower pressure.

In the erosional theory, it is believed that drumlins form simply as the result of currents of floodwaters washing away till material from a localized dense source. This would suggest that zones of localized till material were moved into position by glacial movement and later eroded by the action of meltwaters.

Below is an example a drumlin in Northern Ireland:

Drumlins are found all around the world. In North America, they are most prevalent in Canada, with drumlins located in all provinces and territories. The largest drumlin fields in the world are found in Nunavut, the Northwest Territories, northern Saskatchewan, northern Manitoba, northern Ontario and northern Quebec. In North America, they are most common in central New York, the lower Connecticut River valley, eastern Massachusetts, the Monadnock Region of New Hampshire, the central and southern lower peninsula of Michigan, Minnesota, the Puget Sound region of Washington, and Wisconsin.

The drumlins you are visiting today are part of the Chautauqua drumlin field, an area encompassing parts of northwest Pennsylvania and southwest New York where over 750 drumlins have been identified. The area here in Erie County includes the only drumlins located in Pennsylvania. There are multiple drumlins located in these gamelands, so this area could be considered a swarm. The topography of such an area is sometimes called a "basket of eggs" topography, as shown in the diagram below.

Below is an example a swarm of drumlins in Canada: