On the Rocks at Pemaquid Point

Yesterday dawned cool, sunshiny and slightly breezy–the perfect day for a 2+ hour drive and an outdoor exploration. And so I had the extreme pleasure of joining a small group of naturalists for a geology lesson offered by one of our colleagues, Denise Bluhm, at Pemaquid Point in mid-coast Maine.

p1a-Pemaquid Point Lighthouse

The lighthouse is one of 57 still active along the Maine coast and it’s this very one that is featured on the state quarter. It was manned from 1927-1934, but has been on automatic ever since.

p2-Pemaquid Point on map

But that wasn’t our focal point. Instead, we’d gathered to learn about the rocky coast below. After reviewing the definition of mineral (naturally occurring solid, distinctive physical properties, e.g. cleavage, hardness, crystal form and color, and characteristic chemical formation) and rock (one or more minerals together, aka mineral soup), Denise pulled out a geologic map of Maine and pointed to our location.

p3-map :Brunswick formation direction

She then oriented us northeastward and helped us understand that we were standing on what is known as the Bucksport formation, a deposit of sandstone and mudstone metamorphosed into a flaky shist. And then she took us through geological history, providing a refresher on plate tectonics and the story of Maine’s creation–beginning 550 million years ago when our state was just a twinkle in the eyes of creation.

p4--do you see the fold?

Stepping below the lighthouse, Denise asked if we saw the fold. I thought I knew what she pointed to, but . . .

p5-layers in beds

it took more of her insight to fully form the picture for me. The metamorphic rock, it turns out, is on its side due to intense pressure in its long-term history and thus we could examine its layers, much like the rings on a tree. That doesn’t mean I could age it, but just understand that over time various pressures and results of heating and cooling events caused the variation in color and mineral size of the bands. Lighter gray=sand and silt (composed of sea sediments), Medium gray=quartz, feldspar and biotite mica (black). Darker gray=more biotite. Greenish-gray=limy sand and silt. Rust=iron. All of it equals a gneiss (nice) or layered formation with foliation.

p6-zigzag

I think one of my favorite learnings came from the sills and dikes that show their faces throughout the rock. Sills are parallel or perpendicular intrusions while dikes run off parallel. And this particular dike featured a zigzag created by a continental collision. The Z-fold, as she referred to it, was caused by a right lateral shear. Who knew?

p9-first fold understanding

My understanding of the first fold Denise had pointed to began to develop more fully when she pulled out a geological compass and measured the angle of the rock to the left and then we could see the same angle on the far right and suddenly in my mind’s eye was the arc that has since eroded. With that came the new knowledge that more moons ago than my brain can comprehend, mountains reached six miles above and natural forces had eroded their 12,000-foot structures.

p10-dike to lighthouse

We crossed the rock from feature to feature, occasionally looking back at the lighthouse to note characteristics, such as the igneous dike (lighter color) that cuts across the metamorphic rock and leads to the buildings. Being made of granite, it offers a solid foundation for the tower.

p11-Denise on fold

And then our great leader led us to her favorite feature–the greatest fold in Maine.

p11a-the fold

Though the rocks were originally horizontal in nature, intense pressure and heat at some point in their lifetime forced such folds.

p12-everyone on fold

It was worth a photo call for Denise, Sharon, Judy, Karen and Penny–all sharing a brain with me for the day.

p13-the big dike

From there, we had a great view of the large granite-topped sill that is harder and thus more resistant to erosion.

p14-sunburst lichen

As we made our way back across to it, we paused to look at quartz, feldspar and biotite mica–but lichens such as the sunburst also caught our attention.

p15-lichen disks

Don’t tell Denise. But do check out those fruiting bodies–the apothecia.

p16-fold looking toward lighthouse

Suddenly, our eyes and brains recognized the fold formation throughout.

p19-Karen at dike

At the huge sill, Karen posed to give a sense of height. (Ignore photo light)

p22-bucksport layers

And then we looked at its structure–metamorphic below and granite pegmatite with huge crystals above.

p23-swirls

We noted swirls and imagined silly putty (invented in a barn in my hometown of North Branford, Connecticut).

p24-under the sill

And stood in awe of life.

p25-large crystals

I mentioned the large crystals–evidenced here. Far larger than the 2.5 centimeters that defines a pegmatite.

p26-Denise again

Denise showed us some popcorn migmatite and how the schist and pegmatite formed together.

p29-igneous rock formation 2

One of our next stops was atop a jetty–so different in structure. This is an example of an igneous rock intrusion created deep underground.

p30-trough of a syncline

To its side we could see a trough–known geologically as a syncline.

p33--garnets

Through her eyes, we spotted red specks of garnet.

p33--buodoin--sausage 1

And began to understand the pinching and swelling from compression and shearing to the Northeast that formed sausage-shaped boudins.

p31a--pressure formation

Closer to the lighthouse, we noted the isoclinal folds Denise referred to as S-folds (compared to the Z-folds we’d seen earlier).

p35--view

Before the day began, this was a great example of the rocky coast of Maine.

p36--view from lighthouse

But when we climbed the lighthouse tower after our lesson, we looked below with brand new eyes and understandings (and still so much more to learn and wrap our brains around).

Thankful were we for our day spent in wonder on the rocks at Pemaquid Point with Denise.

 

Mondate By the Bay

After lunch at Gritty McDuff’s in Freeport (haddock sandwiches and a brew–no PB & J today), my guy and I found our way to Wolfe’s Neck Woods State Park on Casco Bay. So, here’s the good, but scary part. We’ve been there before, but not in a long while–and neither of us had any recollection of it. That means today’s visit was like going there for the first time all over again. (Our dementia is setting in.)

map

Trails follow the coast and circle back to the Harraseeket River, passing through a variation of natural communities. We trekked over all but the North  Loop before we ran out of time. Actually, we finished up a wee bit after the park was officially closed for the night and were glad to find the gate still open.

red oak

By the forest floor, it was easy to name the predominate hardwood trees in any given area from Northern Red Oak to

beech leaves

American Beech to

big tooth aspen leaves

Big-tooth Aspen. Spruce, hemlock, pine and fir also fill this more than 200-acre forest given to the State in 1969 by Mr. and Mrs. Lawrence M.C. Smith.

down the trail

Sometimes the path was packed dirt that made for easy walking.

stone pathway

In other places, a stone pathway had been carefully laid out before us.

roots

And no woodland trail is complete without an array of roots and rocks.

blow downs

One of the noticeable features of this location is the number of uprooted trees.

blow down dominoes

The wind enjoyed a serious game of tic, tac, toe, three in a row or dominoes with this event. Here’s hoping that no one planned a picnic that day.

blow down every which way

And in other spots, it looked like the gale force winds of both summer and winter beat upon the landscape.

curves

Always on the lookout for interesting sites, my eye was drawn to the wavy inner bark of this old birch. It could be locks of Rapunzel’s hair. Of course, I also see a mermaid swimming in the slightly darker wood. Isn’t that what a naturalist is supposed to see?

eye in the tree

And then there was the hemlock-green sideways-turned eye–taking a different view of the world.

pine needles

While I’m sharing some interesting shots, I thought I’d include this one–of pine needles. It was getting dark and I chose the wrong setting, but I like the artsy texture of it–tweed-like in appearance.

seeing red

And the most interesting of all. My guy–he could pass for the invisible man.

Casco Bay Islands

Of course, we were beside Casco Bay, so we spent time exploring the coast line as well.

islands floating in distance

My knowledge of the island names is less than limited, but it did appear that those in the distance were floating on water–a mirage.

Goggins Island

As part of the park, Goggins Island is an Osprey sanctuary. Though I respect that, I do have to wonder about the human impact on the bird’s mating season. We’ve seen Ospreys build nests atop telephone poles over highways and bike paths with successful births despite the continuous noise and disturbance. But . . . a sanctuary certainly provides an extra layer of protection.

osprey platform

We could only spot one cock-eyed nesting platform on the island–with no nest on it.

Osprey nest 1

We did spy a bird-made nest on the mainland, and rather close to the trail. Just saying.

Googins in sunlight

All nests are abandoned now as the birds flew to South America in September–with plans to return next year to this golden paradise where they’ll mate again. Ospreys are monogamous and repeatedly use the same nest site. That’s the amazing piece to me.

rocky coast

The rocky coast of Maine includes the lighter colored granite pegmatites and darker metamorphic rocks with their repetitive flattened layering.

islands--lines in the rock, sea and sky

I found it intriguing how each layer before us mimicked the next–from the rocks to the ocean waves to the islands to the clouds in the sky.

late afternoon light

And then it was time to bid adieu. The setting sun where the forest meets the bay–Casco Bay. On. A. Mondate.