It’s time for fall foliage in many places, especially the northeast United States, so this week, we will head to New Hampshire to take in the colors and geo-sites. You can check out this Fall Foliage Prediction Map for the contiguous United States here, or this Foliage Tracker for the White Mountains of New Hampshire here. Pack your camera and your favorite flannel and beanie combo!📷🍂
Sharon Lyon
Editor, GeoLifestyle
Flume Gorge, Franconia Notch, New Hampshire
Michael Paixao/Shutterstock.com
New Hampshire is known as the Granite State for its outcroppings and long history of quarrying. To see the granite up close, hike the Flume Gorge, located in Franconia Notch State Park, in the White Mountains. This scenic natural granite chasm extends 800 feet at Mount Liberty’s base.
Area geology: The White Mountains are part of the Appalachian Highlands Physiographic Province and are the most rugged in New England.
The bedrock of the White Mountains is mostly Devonian-age granite and schist, metamorphosed and uplifted during the Acadian Orogeny.
Mount Liberty is composed of Jurassic-age Conway Granite, intruded around 180 million years ago and part of the White Mountain plutonic-volcanic series.
Conway Granite is a pink, biotite granite containing a relatively high concentration of thorium.
During the last Ice Age two million years ago, the ice covered the top of the White Mountains. Abrasion from glacial sediments carved U-shaped valleys, one of which is Franconia Notch.
Hike the Flume: Check out the granite walls and spectacular mountain views as you hike the two-mile elevated wooden boardwalk. Be ready for stairs!
Trip tips:
Along this self-guided nature walk, experience cascading mountain pools and waterfalls, glacial boulders, covered bridges, and the Wolf’s Den, a kid-friendly cave.
Reservations are required, so book in advance.
The Gilman Visitor Center features a gift shop and food court should you need to refuel or take a short rest.
Sean Kimiagar stopped by to visit with Spotfire at IMAGE to hear about the Spotfire visual data science platform and how it empowers engineers with cutting-edge, energy-specific capabilities to gain operational and strategic insights from complex data.
The Old Man of the Mountain–A Lesson in Weathering and Erosion
Neil Bowman/Shutterstock.com
The Old Man of the Mountain was a human-like profile composed of a series of granite ledges on the side of Cannon Mountain in Franconia Notch, New Hampshire. This natural rock formation stood 40 feet tall, 25 feet wide, and was located 1,200 feet above Profile Lake.
Regional history: The Old Man (also called Great Stone Face) was culturally significant to indigenous groups such as the Abenaki and the Mohawk.
In 1805, surveyors first documented the formation.
In 1945, the Old Man of the Mountain became the New Hampshire State Emblem. It appeared on license plates, and in 2000, it was featured on the state quarter.
Area geology: Cannon Mountain is composed of the Jurassic-aged Conway Granite.
At the end of the last Ice Age, after glacial retreat, freeze-thaw produced the five ledges making up the Old Man on the exposed walls of Franconia Notch.
Weathering at work: Freeze-thaw continued to open more cracks in the granite. The formation needed artificial support for decades through structural reinforcement with cement, rods, and chains.
You can’t beat mother nature: The Old Man collapsed on May 3, 2003, but you can still visit the site and see steel recreations of the formation from specific angles.
Ruggles Mine is a former large open-pit and tunnel mine located on Isinglass Mountain. Most of the tunnels were erased by the widening of the open pit. Now, you can collect minerals and rocks on the dump piles of the mine.
Area geology: The wall rocks are medium-grained quartz-mica schist, coarse-grained biotite gneiss, and amphibolite of the Devonian-age Littleton Formation. These were intruded by granite pegmatite.
Mica mining began in 1803. Muscovite is the most abundant mineral at the mine, with large books within the pegmatite.
Quartz and plagioclase are plentiful, and perthite is graphically intergrown with the quartz. Beryl is also found and was mined.
Feldspar was mined from 1912 to 1969. One grade of feldspar was used in the manufacture of Bon Ami scouring powder. Another grade was used for ceramics manufacturing.
In 1962, the U.S. government’s stockpile program that purchased mica and beryl ended, and the mine eventually closed.
More mine minerals: The mine is famous for uranium minerals. ‘Gummite,’ a mixture of uraninite with secondary uranium minerals, was discovered in 1936.
Close to the radioactive minerals, the quartz is smoky.
Also found at the mine are apatite, almandine, galena, goethite, pyrite, staurolite, and zircon. A complete list is available here.
Rockhounding tips: Digging is allowed on the mine dumps, but no hammers or chisels are allowed.
You can mine up to a five-gallon bucket of rocks and minerals per paid admission. Children under 10 are free.
The mine is open Thursdays–Sundays. The 2025 season closes 12 October.
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