See Where Two Oceans Meet But Do Not Mix (Photo)

A picture from the Gulf of Alaska that has been making
the rounds on the Internet for the last few years —
though particularly in recent weeks — shows a strange
natural phenomenon that occurs when heavy, sediment-
laden water from glacial valleys and rivers pours into the
open ocean.
There in the gulf, the two types of water run into each
other, a light, almost electric blue merging with a darker
slate-blue.
Informally dubbed “the place where two oceans meet,”
the explanation for the photo is a simple one, though
there are many misconceptions about it, including that
catchy title.
In particular on popular link-sharing website Reddit,
where users have on multiple occasions erroneously
attributed the photo’s location as “Where the Baltic and
North Sea meet” and the two types of water as being
completely incapable of ever mixing, instead perpetually
butting against each other like a boundary on a map.
You also may have seen a variation on the photo
featuring the same phenomenon, taken by photographer
Kent Smith while on a July 2010 cruise in the Gulf of
Alaska.
That photo too has been circulating the web for some
time, though the misconceptions about it seem to be less
thanks to Smith’s explanation of the photo on his Flickr
page.
That one has also been making the rounds on Reddit and
social media for years, and had racked up more than
860,000 views by early 2013 on that one page alone,
Smith said.
That original photo, however, originates from a 2007
research cruise of oceanographers studying the role that
iron plays in the Gulf of Alaska, and how that iron
reaches certain areas in the northern Pacific.
Ken Bruland, professor of ocean sciences at University of
California-Santa Cruz, was on that cruise. In fact, he was
the one who snapped the pic.
He said the purpose of the cruise was to examine how
huge eddies — slow moving currents — ranging into the
hundreds of kilometers in diameter, swirl out from the
Alaska coast into the Gulf of Alaska.
Those eddies often carry with them huge quantities of
glacial sediment thanks to rivers like Alaska’s 286-mile-
long Copper River, prized for its salmon and originating
from the Copper Glacier far inland. It empties out east of
Prince William Sound, carrying with it all that heavy clay
and sediment. And with that sediment comes iron.
“Glacier rivers in the summertime are like buzzsaws
eroding away the mountains there,” Bruland said. “In
the process, they lift up all this material — they call it
glacial flour — that can be carried out.”
Once these glacial rivers pour out into the larger body of
water, they’re picked up by ocean currents, moving east
to west, and begin to circulate there. This is one of the
primary methods that iron — found in the clay and
sediment of the glacial runoff — is transported to iron-
deprived regions in the middle of the Gulf of Alaska.
As for that specific photo, Bruland said that it shows the
plume of water pouring out from one of these sediment-
rich rivers and meeting with the general ocean water. It’s
also a falsehood that these two types of water don’t mix
at all, he said.
“They do eventually mix, but you do come across these
really strong gradients at these specific moments in
time,” he said. Such borders are never static, he added,
as they move around and disappear altogether,
depending on the level of sediment and the whims of the
water.
There is much study being conducted on how this iron
influences marine productivity, in particular its effects
on the growth of plankton, which Bruland referred to as
“the base of the food chain.”
But rivers aren’t the only way that glacier sediment finds
its way into the Gulf of Alaska — occasionally strong
winds can whip up enough silt to create a cloud of dust
that’s visible even from space as its being carried out to
sea.
So next time somebody shares a “really cool photo” of
“the place where two oceans meet,” feel free to let them
know the science behind the phenomenon. After all, in
this Internet age,