Local Glacial Features
Here we present the top-secret information we have gathered throughout our expedition of areas surrounding LSRHS for the people of America to tour. We have risked life and limb so that you can view this from the safety of your own home. A worthy sacrifice.
As we know, our good friend the Laurentide Ice Sheet created much of the topography of the area, and that is what we have focused our mission on. For a detailed overview on the types of features below, see /glacial-features-overview.html
As we know, our good friend the Laurentide Ice Sheet created much of the topography of the area, and that is what we have focused our mission on. For a detailed overview on the types of features below, see /glacial-features-overview.html
Maps/Government Secret Satellite Surveillance Footage
For Reference
The first feature we have disclosed is the hill across Concord Rd. from LSRHS where Shaq (a great American hero) used to live. Shockingly, this hill is a drumlin that was created during the last time the Laurentide Ice Sheet passed over New England. How are we so sure you ask? Well, if you remember the information about drumlins and kames, you'l recall that they are both small hills (like this one) but that the sediment that makes up kames is stratified, while the sediment that makes up drumlins is unstratified, and that kames are steep on all sides, while drumlins have a steep side that faces where the ice sheet came from, and a gentle side that faces away. As you'll see below, the sediment here is most defiantly unstratified, and their are two distinct gradients as well. In addition, the USGS does not tolerate being talked back to. If you want to know more about drumlins (and we know you do!) be sure to check out /glacial-features-overview.html
Next on our expedition was the Great Meadows National Wildlife Reservation. We looked at a particular hill next to the Concord River and the visitor's center. After careful investigation, we have concluded that this hill is too a drumlin. Below is our evidence for that claim. This drumlin is no different from any other one, and the explanation for how it was formed can again be found at /glacial-features-overview.html
Also at Great Meadows National Wildlife Refuge, there is a bowl-shaped depression on top of the drumlin. This depression is a kettle hole that was formed by a retreating ice sheet 15,000 years ago. As it retreated, a block of ice broke of from the glacier on top of this hill, and the glacial sediment covered it. When it got warm enough for the ice to melt, it left this bowl shaped hole in its place. More info on kettles over at /glacial-features-overview.html
Last, but certainly not least, on our expedition is the woods behind Lincoln-Sudbury Regional High School. Here we explored three main features (see map right). First, feature A (in green) and the other, smaller hills around it make up a kame delta, which is a group of kames. We know because they are all steep on all sides and made of stratified sediment. Feature A would be rounded like we know kames are (/glacial-features-overview.html) if it weren't for feature B cutting a side out of it. These kames were likely created 15,000 years ago when the Laurentide Ice Sheet was retreating from the area. For a detailed explanation of kames, check out /glacial-features-overview.html!
Feature B consists of two bowl shaped depressions that cut out the slope of feature A and are filled with water at the bottom. Although the slope was very steep, and we fell multiple times trying to get to the bottom, this glacial feature was still no match for us. Thanks to our great struggle here, we were able to identify these depressions as kettles that filled with water. These kettles were also likely created when the Laurentide Ice Sheet was moving out of the Lincoln-Sudbury area when ice blocks broke off from the sheet and were buried but then melted, leaving these holes. Once again, if you are fascinated by kettles and all their glory, check out /glacial-features-overview.html. These pictures below give a good sense of the two depressions, but tragically, we couldn't get a researcher in them for scale due to the danger of the topography.
Finally, we make it to the final feature before we can call this mission a wrap. This large boulder (pictured below) was found on the cross-country trail north-east of feature A. It can't be a bedrock outcropping, since it is on stratified glacial sediment (see surficial map). Therefore, it must be an erratic - a chunk of bedrock plucked up by a moving glacier and deposited elsewhere when the glacier melts. Erratics are always different from the bedrock below (Tarbuck 164). This one likely came here from a piece of bedrock that the Laurentide Ice Sheet picked up in its travels. A more detailed description of all the non-glacial properties of this erratic can be found at /other-local-features.html