ShoreZone Program Daily Log - July 13, 2018

Day number three and mother nature was smiling sunshine. Although this makes for prime flying conditions it actually is not good lighting for imaging. Sunlight can reflect on the surface of the water and create a blinding reflection when you are shooting down from a helicopter flying at several hundred feet. The extreme contrast in lighting can send the camera’s light meters into a tailspin resulting in under and over exposed photos. Imaging glaciers on a sunny day is also challenging for the same reasons, nothing like a giant piece of ice to reflect sunlight and wash out a photo. While flying we must always be aware of what angle the sunlight is at and where it will be as we wind around tight corners and move under the shadows of steep mountain faces following the contour of complex shorelines. Sometimes there's just no avoiding getting photobombed by the sun. The ideal conditions for imaging the coastal zone are no wind, light cloud cover with a high ceiling (several thousand feet), and no rain. A show stopper for the imaging team is when the fog monster shows up.

Alaska

Tarr Inlet with Russell Island on the left, Glacier Bay National Park.

Tarr Inlet with Russell Island on the left, Glacier Bay National Park

So much going on in this photo one simply soaks in its beautiful composition. Ok, just another pretty picture, what is going on here. The foreground shows a complex area of recurved spit and salt marsh habitat intercepted by a spectacularly large alluvial fan. Both of these features are flanked by a glacially cut inlet. You can even see where the high tide was earlier in the day by the wet band of sediment across the fan and into the salt marsh. Despite this intersection of major geomorphic features, one is drawn to the background of this image wondering what lies around the corner, how far back does it go, could there be a glacier making its retreat? Well, it is called Glacier Bay National Park and Preserve!

Margerie Glacier, Glacier Bay National Park & Preserve.

Margerie Glacier is an icy highlight of any visit to Glacier Bay National Park, and a primary destination for visitors on sailboats, kayaks, tourboats, and cruise ships. It is about 1-mile wide, with an ice face that is about 250 feet high above the waterline, but with its base about 100 feet below sea level. The glacier is about 21 miles long and begins in snow-fields in the Fairweather Range where elevations exceed 9000 feet. The ice flows about 2000 feet per year, or about 6 feet per day. Margerie Glacier joined Grand Pacific Glacier about 1990, but they have since separated as Grand Pacific recedes.

Margerie Glacier is a hanging glacier with its base about 600 feet above the floor of Tarr Inlet near its center. As the flowing ice moves beyond the submerged valley floor, it breaks off and calves into the sea in spectacular fashion.

Margerie’s terminus was relatively stable in position through the 90’s; however, about 1998 the northern third of the terminus began a slight recession, forming a small embayment within the ice face.

Over the years, this part of the terminus has thinned and the embayment has expanded. In 2017, this section experienced dramatic changes with deep embayments and a large mass of bedrock now exposed. Perpetual meltwater discharges from subglacial streams below the water surface within the central area of the glacier resulting in upwellings and occasionally fountains. Where the ocean is disturbed by meltwater streams and calving icebergs, flocks of black-legged kittiwake gulls swarm and glean small marine creatures from the surface.