(Stratham, NH) Stratham Hill Park (Drumlin)

-

 

Panoramic shot of the Stratham Hill Park ground from the fire tower (43.0395, -70.8901), Sunday Jun. 19, 2022, in Stratham, NH.  Credits: Geo Field Report


Recently I've been hooked on some crime mystery TV series.  It seems that for each series, there would be an episode or two involving the "mystery murder weapon" that disappeared into thin air leaving only a smudge on the floor as the clue.  Ice, which melts under room temperature, has inspired many mystery stories.  To me, a mystery on a much grander scale would be how ice has transformed our landscape.  Glacier, a river of ice, is capable to carve out valleys and move rocks.  Some glaciers have disappeared, leaving only clues for us to figure out what happened.

One such clue is the rock deposits left behind.  The smaller rocks are called moraines and sometimes there are bigger pieces that look like hills, these are called drumlins.  Drumlins have some very interesting geographical features: they are usually elongated and look like spindles.  Imagine a huge piece of elongated rock (the drumlin) floating in a flow of ice and other smaller rocks, the huge piece of rock would naturally orient itself so that its longer axis is parallel to the flow.  Additionally, the pointier end would likely point to downstream of the flow.

There are quite a few of these drumlin hills scattered around New England.  For example, there are six such hills in the town of Stratham, NH alone.  Using a topographic map, it's quite remarkable how these hills together tell a story from a long time ago: a river made of ice and rocks flowed through today's New England area, leaving behind these small hills, rock piles, lakes, and other glacial features.  If we can observe these drumlins across a wide area, we may even be able to plot out the course of the glacier even if it has disappeared a long time ago!

Google Map with the terrain layer showing three drumlins: Stratham Hill, Long Hill, and Jewitt Hill in Stratham, NH.


Same map annotated with arrows along the long axes of these drumlins indicating flow of past glacier.


Thinking about the glacial force reminds me of Sir Tennyson's poem.  Though the water flow is not now that strength which in old days moved earth and heaven, we can still seek the clues, and find the awesome stories our land tries to tell us.


Extended reading:

(National Park Service) Drumlins

(Michigan State University) Drumlins

(US Department of Coastal Service) Open Space and Recreation Plan for the Town of Stratham

Comments

Post a Comment

Popular posts from this blog

(Quincy, MA) Moswetuset Hummock (Hummock)

-
Image
  The Moswetuset Hummock as viewed from Quincy Shore Reservation (42.2807, -71.0177), Jul. 30, 2023, in Quincy, MA.    Credits: Geo Field Report The Moswetuset Hummock marker (42.2895, -71.0224), Jul. 30, 2023, in Quincy, MA.    Credits: Geo Field Report I am a huge fan of the food scene in Quincy, MA.  But only recently have I tried to look more into what Quincy offers in geography.  Quincy has a sandy coastline, but one nearby spot caught my eyes, the Moswetuset Hummock. Today, a "hummock" means a small mound or knoll, and often the example pictures show these small mounds in the ground.  But the word had a nautical origin 500 years ago, it meant "a small hill that is conical- or dome- shaped that rises above the coastline".  Hey, that's a very good description of the Moswetuset Hummock! The Moswetuset Hummock has a good bit of history, too.  It is believed to be the location where the Massachusetts tribe first met with the Plymouth colonists more than 400 yea
Read more

"North"

-
Image
A compass Credits: Wikimedia   With the pandemic, I've been staying indoor most of the time browsing the Internet.  While looking around Google Map for ideas on future trips, I noticed something very interesting about the Forbidden City.   Do you also see it?  The Forbidden City is oriented at a small angle counter-clockwise from the true North-South line! I dug a little online, and some have suggested that this deviation is due to the use of compasses in fengshui.  What that means is, the Forbidden City was likely planned along the "magnetic North-magnetic South" line instead of the "true North-true South" line.  The phenomenon that the magnetic North differs from the true North is called magnetic declination or magnetic variation. The exact cause of magnetic declination is complicated, but the short version is that the magnetic materials in the earth's crust are not perfectly aligned with the true North and true South.  Imagine suspending a bar magnet in
Read more