Alaska's Magnificent Coastline

Alaska has an extensive coastline, longer than that of all the other US states combined. Some estimate it to be more than 49,000 miles lone, and most of it is remote and uninhabited. Now thanks to the ShoreZone project, some 38,000 miles of the Alaskan coastline has been photographed and can be viewed in sharp detail.

The project was developed in 1989 in order to access damage caused by the Exxon Valdez oil spill. Since then it has been used to gather habitat information of plants, animals and fishes, review applications for industrial permits, assess the risks posed by eroding shorelines and rising sea levels, and monitor the spread of invasive species and marine debris. These images along with useful data were long available to the public, but it’s the first time they are available on an interactive website, not unlike Google Earth.

Tracy Arm, Snettisham Peninsula, Southeast Alaska August 04, 2008. A fringing salt marsh of sedges lines the shore of this fjord, and behind that a successional community of terrestrial grasses, alder bushes, and spruce trees.

While the images available on Google Earth and Google Maps (aside from Street View) are satellite imagery, the images on ShoreZone were taken from a helicopter traveling at an altitude of 100-300 meters. Shooting from a helicopter, rather than grabbing images from the satellites, allowed them certain flexibilities, not to mention the ability to capture gorgeous details that wouldn’t have been possible from a satellite hundreds of kilometers up.

The shooting schedule was very precise. They shot during the 5 days of each month when the tides were its lowest in order to show as much of the coastline as possible. On each of those days they only had a 4-hour low tide window. Satellite images for those exact times wouldn’t have been possible. Even if it were, clouds would have probably blocked the view.

More importantly, the helicopter offered an oblique view of the landscape, revealing surface features in three-dimensional relief that can’t be seen in straight-down satellite images. “We have some very complex shorelines,” said NOAA Fisheries biologist Mandy Lindeberg. “Small island groups that you have to circle around, rock reefs, inlets, deltas. We can’t get the detail and scale we need for habitat mapping unless we’re flying tight around those features.”

The images themselves are some of the finest examples of scientific photography. Although shot primarily to help professionals manage the resources in this area of the planet, the exquisite colors, contours, and textures in these beautiful images can help us all appreciate the fragile environment that is slowly being destroyed by rising seas, increasing industrial development and human-made disasters.

All photos credit: ShoreZone.

Grewingk Glacier River, Kachemak Bay, Cook Inlet. June 24, 2009. Rivers emanating from retreating glaciers carry large volumes of sediment, producing braided river patterns with multiple channels. During periods of relative stability, opportunistic animals such as the blue mussel (Mytilus trossulus) and marine algae such as the rockweed (Fucus distichus) may colonize the beach face, creating the beautiful colored patterns seen here.

Point Nowell, Knitght Island Passage, Prince William Sound, July 3, 2004. The rock forming these mainland sea cliffs are of the Valdez Group and are composed of tightly folded and metamorphosed marine greywacke and dark gray slate with granite intrusions. The relatively uniform slope of this sea cliff allows for well-defined vertical zonation of intertidal organisms with the black lichen (Verrucaria maura) in the supratidal, the brown rockweed (Fucus distichus) in the high zone, and a new set of barnacle recruits in the mid zone. A small section of the low zone is visible near the waterline where larger adult barnacles (Semibalanus cariosus) dominate the rock surface.

Prince of Wales Passage, Prince William Sound July 1, 2004. Sea cliffs in Prince William Sound erode primarily by thermal expansion of freezing groundwater seepage and rain water. The broken rock particles tumble into the sea and accumulate as talus at the base of the sea cliff. Ocean waves and currents act only to remove the finer particles from the debris pile. The vertical structure of the columnar basalt is emphasized in this image by intertidal plants. The upper extent of marine zonation on rocky shores in Prince William Sound is typically indicated by a horizontal band of black lichen Verrucaria maura occupying the portion of shore above the highest tide level and wetted only by sea spray.

Tignagvik Point, Kamishak Bay, Cook Inlet June 25, 2009. Waves erode coastal rocks and often create shore platforms like this one. These platforms become colonized by marine plants and animals and support prolific algal growth. Winter ice floes carried by Cook Inlet currents scour away all but the most persistent plants and animals from the rock, often leaving a bare surface for new recruitment of plant spores and animal larvae the following spring.

Mills Bay, Kasaan Bay, Prince of Wales Island, Southeast Alaska July 13, 2007. When a large rock or island is near the shore and the space in between is filled with shallow water, sediments can accumulate if the in-between zone is protected from wave attack. Eventually, a spit forms, linking the mainland to the offshore island. This type of spit is called a Tombolo. You can get a sense for the underlying sediments based on the colors of the vegetation. Rust-colored Rockweed (Fucus distichus), a perennial, grows on stable sediments, while the ephemeral ulvoid seaweeds, which are green, grow on less stable sediments.

Cape Magdalena, Dall island, Southeast Alaska July 28, 2007. Dall Island contains deposits of marble, some of which have been commercially mined starting in the early 20th century. The marble stratum shown here, on the West coast of Dall Island, is vertically dipping—that is, it lies straight up and down. This exposes the relatively soft marble to weathering, and it erodes faster than the harder surrounding rock. Layers of shale and slate are interspersed with layers of marble, causing the alternating light and dark bands.

Tracy Arm, Southeast Alaska Mainland August 4, 2008. This area was recently exposed by retreating glaciers. Below the thin line of black lichen is a bare band that shows where ice has scoured the rock clean. Higher up, above the tidal zone, the steep slope and lack of soil makes for a marginal terrestrial habitat.

Brownson Island, Ernest Sound, Southeast Alaska May 06, 2008. A tidal race is a rapid formed by fast-moving tidal currents rushing through a constriction. Ernest Sound in Southeast Alaska has a tidal range of up to 7 meters, which forces great volumes of seawater through the many surrounding inlets and embayments. As the tide rushes out, water surges through these narrows in turbulent rapids and whirlpools.

East Bight, Nagai Island, Shumagin Islands, The Aleutians May 16, 2011. Regularly-spaced beach cusps are formed by wave action that deposits coarser sediments at the point of the cusp and finer sediments behind. The alongshore spacing is related to wave height and can range from less than a meter to tens of meters. Once formed, beach cusps can be self-sustaining if the prevailing wave pattern remains stable.

Oruktalik Entrance, near Tapkaurak Point, Beaufort Sea August 1, 2012. An inlet cuts a barrier island, allowing water exchange between the Beaufort Sea (upper half of image) and Oruktalik Lagoon. The fingers at the tip of the barrier island are called spits and are formed by waves that travel parallel to the island. Each spit likely represents a pulse of sediment deposited during a storm.

Mary Sachs Entrance, near Prudhoe Bay, Beaufort Sea August 4, 2012. The complex of spits on this barrier island extend like fingers into the Beaufort Sea which remains frozen for about nine months of the year. Many of the Beaufort barrier islands are migrating landward at rates of 20 meters per year or more, moved by storm surges when waves carry large volumes of sediment. This process is an example of what geologists call “episodic uniformitarianism,” in which the landscape is shaped by infrequent, high-energy events.

McClure Islands August 4, 2012. Blocks of ice are stranded on the inside of this barrier island, while the pack ice is visible on the horizon. This barrier island persists as storms and pack ice continue to deposit logs and sediment on its shores.

Thaw Lake, Prudhoe Bay August 5, 2012. An oil pipeline follows the shoreline of an encroaching lake (lower left) in this oil-rich province not far from the coast of the Beaufort sea (visible in the far background). The low tundra is gradually becoming submerged as the permafrost melts and subsides. At some point, this pipeline may need to move.

Kivalina, on the edge of the Chukchi Sea Humans have been a part of the Alaskan Arctic coastline for thousands of years. In recent times, their villages have consolidated and include permanent infrastrucutre such as roads, runways, and power generating stations. Being located just a few meters above sea level, communities such as Kivalina are under constant threat from the sea and are vulnerable to storm surges and rising sea levels. The shorelines of Kivalina are eroding on both the seaward and lagoon side of the barrier spit on which the village is built.

Between Fish Creek and Nechelik Channel, Harrison Bay August 6, 2012. A landscape disappears as tundra slips below sea level. As tundra thaws, it subsides, resulting in a characteristic polygon fracture pattern. The sea invades along these fractures and floods the sunken centers of the polygons. Logs stranded on the rims of the polygons (white in color) show that this entire area is submerged during storm surges. Very small changes in sea level or water level will inundate this low tundra and contribute to further thaw subsidence.

South of Cape Halkett, Harrison Bay August 6, 2012. A tundra surface is under duress as ice wedges thaw along fracture lines and water accumulates in small thaw lakes. A drained thaw lake (foreground) is showing advanced stages of thaw subsidence – almost every fracture is filled with standing water and more than 50% of the tundra is covered in thaw lakes.

Sources: NOAA / Alaska Dispatch News