Wednesday, June 19, 2013

The Long View: Watching the Earth Move

It surprised me when I read that you could see Mount Washington from a hilltop in Falmouth, so when I climbed Stone Ridge, I was impressed with the amazing view.  My first visit on a clear day in April gave me a Kodachrome view of the mountain and the broad landscape between here and there.  It wasn't until much later that I realized that this might just be the perfect perch from which to watch the earth move.

Of course the White Mountains were just the starting point (well, really Mount Royal in Montreal, Canada, but you can't see that far).  One hundred eighty million years ago there was a hot spot under what would one day become eastern New Hampshire.  In geology, a hot spot is a thin stream of Earth's heated innards bubbling up towards the surface over a long period of time.  When the hot spot underlies a continent the result is violent, explosive eruptions at the surface.  These eruptions and the super-heated magma below the surface built the White Mountains over twelve million years.

The hot spot never moved, and it never stopped bubbling.  The good news for the residents of North Conway, is that New Hampshire did.  When Pangaea split apart, opening the Atlantic Ocean, North America pushed westward, and Africa pushed (relatively) eastward.  By one hundred twelve million years the continent had moved to the point that the hot spot underlay Denmark, Maine, building Pleasant Mountain.  By one hundred eight million the Earth was bubbling in Brownfield, forming Burnt Meadow Mountain.  

The View from Stone Ridge in Falmouth.  Burnt Meadow Mountain is in the center, the White Mountains on the right, and Pleasant Mountain in between.  All are highlighted in red. (a lot of time on Google Earth may not have made up for poor spatial ability; leave comments if you think I've misidentified the mountains).
Soon after the North American continent escaped the fiery clutches of the hot spot, but the hot spot didn't quit.  Between 100 and 75 million years ago it left a trail of underwater mountains (called seamounts) stretching from the continental shelf to the mid-ocean ridge.  At that point, the seamounts seem to sputter out, that is until they emerged on the opposite side of the ridge, where as recently as 10 million years ago they appeared to be approaching Africa and the Canary Islands (or really Africa was approaching the hot spot).

Of course we can't see all of that from Falmouth, but we can see a few million years of continental progress, before the horizon shades our view.  On a clear day, the White Mountains are visible and Pleasant and Burnt Meadow Mountain can be seen as well.  The picture provides not just beautiful scenery, but a window into the tectonic motion that occurs over millions of years.

"Science Reference: Hotspot (geology)." ScienceDaily. ScienceDaily. Web. 19 June 2013. <>.

Girty, G. H. "Chapter 2: Volcanoes." Perilous Earth: Understanding Processes Behind Natural Disasters. Department of Geological Sciences, San Diego State University, June 2009. Web. 1 June 2013.<>.

Watling, Les. "Geological Origin of the New England Seamount Chain." NOAA Ocean Explorer Podcast RSS. Web. 19 June 2013 <>.

Zartman, R. E. "Geochronology of Some Alkalic Rock Provinces in Eastern and Central United States." Annual Review of Earth and Planetary Sciences 5.1 (1977): 257-86.

1 comment:

  1. Fascinating! I had no idea a hot spot formed those mountains. Is there still igneous rock there or has it metamorphized?