Return to Tracy Arm: Rock and Ice in Motion

July 30, 2008: Pybus Bay to Windham Bay to Tracy Arm

Rock and ice in motion

Windham Bay is misty in the early morning. It is a gloomy spot on the mainland of Stephen’s Passage. The sun is incognito. We haven’t come all this way to show Drew and Lucy mist and fog.

Out into Stephen’s Passage we motor, thinking sun. All is still as glass. I photograph the eerie mists that cling in otherworldly patterns through the tree line. It exudes magic: as if somewhere in the spruce, hemlock, and cedar forests huge cauldrons boil.


Eerie mists cling in otherworldly fashion to the tree lines

Up Stephens’s Passage we continue to motor through the glass waters. On our starboard, Sumdum Glacier appears in a burst of sunlight. Blue sky! This is my first time seeing it. Bold and imposing. Breathtaking: several thousand feet above sea level.


Sumdum Glacier

About 50 miles southeast and short of Juneau, we turn into the entrance up Tracy Arm. The red buoy on the right gets swept by strong current—so line up the markers on land and enter a magic kingdom.

Tracy Arm is about 20 miles long—from the western edge of the coastal mountains eastward to tidewater glaciers. Holkham Bay is on our left. We see the the New Zealand boat from Baranof Warm Springs at anchor.

“That’s a possibility for tonight’s anchorage.” Russ says as we pass by.

The shallow water that crosses the midsection of the bay barely covers the end moraines of the glaciers that carved the fjord. The steep slopes resting on metamorphic rocks lead me to wonder how all this incomprehensible matter was formed, was placed by time into a towering, fractured architecture—graced by hanging gardens of fragile plants, trees, and flowers growing at dizzying heights. Drenched by the mists of weeping, cascading, gushing waterfalls.

Through this fjord waters run in the colour of bottle green, graduating to turqouise to milk blue. And on this body of water—floating at a good clip—are myriad shapes and sizes of icebergs broken off of the glacier (calved): a swimmer, a whale tale, swiss cheese, elephants, balancing acts, two in a canoe, ballerinas. They float because the density of ice is less than that of ocean water. Large icebergs rise about 16 ft above water. Medium-sized pieces, called bergy bits, are between 3 and 16 ft above water and are less than 30 ft across. Growlers extend less than 3 ft above water and are less than 20 ft across.

Overwhelmed by the immense beauty, I turn to Harold Stowell’s Geology of Southeast Alaska, Rock and Ice in Motion with these few quotes to shed informed light.

"One of the spectacular consequences of the dense interlocking ice crystals is the blue color that we see in freshy broken icebergs and glaciers. Sunlight includes all of the colors, or wavelengths, of visible light. The low-energy wavelengths, such as red and yellow can be absorbed during travel through glacial ice. These absorbed colors cannot be seen in the surface. Higher energy wavelengths, primarily blue, are not absorbed, but instead exit the ice surface to reach the eye of the beholder. Glaciers frequently appear white rather than blue because air bubbles, fractures, and pitted surfaces from expossure to air and rain scatter light." (p. 14)

Marilyn’s shot showing the blue, high-energy wavelength exiting through the ice surface


Another shot of blue: Swiss cheese

Free ride: white on blue crystal

Drew hand carries crystal ice

Reflection

I continue with Stowell’s description of rock.

"The nearly vertical bare rock faces east of the entrance are carved into igneous plutons and high-temperature metamorphic gneiss that is more resistant to the forces of erosion. These resistant rocks preserve wonderful examples of the information that geologists use to interpret the landscape as glacially carved. Spectacular horizontal glacial grooves have been cut into the solid rock along the walls of the fjord. U-shaped valleys can be observed at waterline or up along the steep slopes along both sides. These valleys are all hanging valleys with respect to the bottom of the fjord; which is more than 1000 ft below sea level. Aretes that once separated the flowing tributaries of ice that carved the valleys now separate some of the valleys. Pointed mountain peaks or horns can also be seen; these mountains were formed at the head of valley glaciers that were flowing in divergent directions away from the peak.” (p. 84)

Vertical bare rock faces are more resistant to the forces of erosion

Tremendous forces were imposed on the rock during glacial flow, which left striation-covered walls scoured inconceivably by rocks dragged across the surface.

Striation-covered walls scoured by rocks dragged across the surface

U-shaped valley

We’ve come a long way—as far as we can through extravagant geological formation. Russ or Drew at the helm, dodging carved icebergs, bergy bits, growlers. Tracy has come to the end of her Arm. We are just short of full site of Sawyer glacier. The fjord is choked with ice. We can see the top pathway of the glacier in its white-blue lava-like flow. What we missed seeing is the ‘looming’ 500 ft wall of ice that extends from the bottom of the fjord to the top of the active glacier, perhaps calving at this very moment.

The top pathway of Sawyer Glacier at Tracy Arm

We are content. Turn the engine off. Float. See the waterfall cascade, carving its own shape with time.

Drew had netted some crystal icebergs on the way. Enough to fill the freezer and cooler. Lucy introduced a serious-looking blade to the ice—chips for our glasses. Drew added rum and peach mango juice. I added a ring of lime. We held our glasses to the sky, with smiles of gratification for a glimpse in time at what the elements worked at shaping for millions of years. Stunning beauty. Salute.

Drew nets crystal ice

Lucy getting serious about chipping ice for our drinks

Slowly we empty our glasses. Again I held mine full to the sky with a piece of frozen time pointing out the rim—crystal ice. We made the return trip mostly in silence, each in or own space. Awe inspired.

“I’m glad I came on this trip.” I heard Lucy softly say.

I raise my glass to the sky

Orcas break the water’s surface preceding Holkham Bay, going inbound toward Tracy Arm. We nose slowly toward a multimillion-dollar yacht at anchor— enough to bring us out of our reality. The sun is setting on Sumdum Glacier. I go out on deck from the warm candle-lit main cabin below for a last glimpse. I see the golden light shine on a far white cruise ship—fire-lit by the sun of a dying day. Zulu gently rocks back and forth. The rock and ice in motion of Tracy Arm continuous on.

Harold H. Stowell’s Definitions
arête	Narrow ridges left remaining between glacially carved U-shaped valleys. These steep-sided ridges often provide beautiful locations for alpine walks and views.
gneiss	A coarsely layered metamorphic rock that forms at moderate to high metamorphic temperatures 500 to 700 degrees C.
metamorphic rock	Any rock that forms within the earth from solid-state recrystallization of pre-existing rock at high temperature and/or pressure.
plutons	A body of or pertaining to magma that has crystallized into an igneous rock beneath the earth’s surface.