Category Archives: Geology

Finding Basalt in the Granite State

Ossipee Mountain Ring Dike (Dia. = 14Km)

Ossipee Mountain Ring Dike (Dia. = 14Km)

On a recent hike into the Ossipee Ring Dike Complex in NH we went looking for Basalt.  To put it simply a Ring Dike is the extinct core of an old (many millions of years old) volcano and Basalt is a rock, quite similar to granite, that is formed from extruded lava that cools under certain conditions to form hexagonal columns.  If you want more info on Ring Dikes and Basalt I’ll include some links at the bottom.

Anyway, The Ossipee Mountain Ring Dike is the largest and most complete ring dike in the U.S. so it follows that there should be lots of basalt there.  Here’s some hiding under a birch tree.

Basalt and Birch Tree

Basalt and Birch Tree

A few years ago we were traveling in the Sierra Mountains in California and we came upon a Geological site called the Columns of the Giants.  This site included some towering cliffs of basalt columns.

How Columns Form

How Columns Form

Columns of the Giants, Stanislaus National Forest, CA

Columns of the Giants, Stanislaus National Forest, CA

Curved Columns

Curved Columns

Columner Basalt and Talus Slope.

Columner Basalt and Talus Slope.

Other examples of Columnar Basalt include Devils Tower in Wyoming (known as the Bear Lodge, by local Native American tribes)

Devil's Tower - Wikipedia Public Domain Photo

Devil’s Tower – Wikipedia Public Domain Photo

and the Devil’s Postpile near Yosemite National Park in California.

"Devils Postpile National Monument near Mammoth Lakes" by Frank Kovalchek

“Devils Postpile National Monument near Mammoth Lakes” by Frank Kovalchek

So our thought was that we might find some similar formations in the Ossipee’s.  Our hike took us to the summit of Turtleback Mountain.

Turtleback Mountain

Turtleback Mountain

The summit of 2203 feet does not have a spectacular view, but it’s a bare summit (is that Basalt or is that Granite) with a nice view and a good crop of blueberries at their absolute peak.

Wild NH Blueberries

Wild NH Blueberries

Two Cedar Waxwings were hanging around picking blueberries too.

Cedar Waxwing - Bombycilla Cedrorum

Cedar Waxwing – Bombycilla Cedrorum

Cedar Waxwing

Cedar Waxwing

Checking for UAVs

Checking for UAVs

After all the hiking, blueberry picking, bird watching, etc. I thought I had better check for unwanted Drones flying around.  Seems from the news that they are just about everywhere these days.  After my nap observations it was only a short hike off the summit to a connecting trail that leads down to a series of gorgeous waterfalls, but still no significant basalt formations.  We did see some nice Fungi though.DSC06660-pretty shroomDSC06632-an interesting growth.And then we found what we were looking for.  A large outcropping of columnar basalt

Columnar Basalt

Columnar Basalt

You must keep in mind that these mountains in the Northern Appalachian Range are almost half a billion years old.  By comparison the Rockies are about 80 million years old and the Sierras and Tetons less than 10 million years old.  These mountains are really, really, old and have been ground down by wind, water, and ice to their current altitude of less then 6,288 feet (Mount Washington).  Who knows how high they were when new, it is believed that the Ossipee Ring Dike Volcano was over 10,000 feet..  And to all our Western Friends who sneer at our puny little mountains, keep in mind that we are often hiking a vertical of over 4,000 feet up 35〫-45〫  talus slopes, across bogs and rivers, and through thick forest with roots that like nothing better than to trip you up. Come on out and try it some day.  But I digress.  What I’m trying to say is; to find an outcropping like this still existing in these old mountains is nothing short of thrilling.

DSC06643-columnar basalt

You can easily see the sharp edged breaks that are so distinctive to this type of formation.

Note the broken hexagonal piece in the lower left of the above picture. Detail below.

Basalt Column - detail

Basalt Column – detail

DSC06649-explanation of columnar

How It Happens

Here you cans see the fracture lines on a large broken piece of the cliffside.

Hexagonal Fracture Lines

Hexagonal Fracture Lines

We were totally blown away with this find and it turned an average hike on a small mountain into a spectacular hike. As we proceeded down the trail we found several of the waterfalls that this region, overseen by the “Lakes Region Conservation Trust“, is famous for.

"Falls of Song"

“Falls of Song”

"Emerald Falls"

“Emerald Falls”

And lastly, for our friend Tom, the requisite fish picture from the small pond at the trailhead.

Rainbow Trout

Rainbow Trout

Plymouth State University – Ossipee Ring Dike

Columnar Basalt – Worldwide

Granite and Basalt (Igneous Rocks)

Obsidian – The King of the Igneous Rocks – at Big Obsidan Flow, Oregon

 

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