That’s one speedy little ice age!

 

The term ice age usually brings to mind a situation continental in scale, and a period millions of years long that ended at the dawn of human history.   What’s cool about Glacier Bay, however, is that it’s a product of a much shorter era that fits squarely into our historical past and our human future.
Officially known as the Little Ice Age, it didn’t really get underway until the late 1600s.  At that time the Hoonah Tlingit people lived in a broad valley that was in the place of today’s Glacier Bay.   Then the glacier at the end of the valley started to move down it, driving the Hoonah Tlingit south across Icy Strait to Chicagof Island, where the good ship Aurora is in their care today.  By 1750 the glacier was as large as it would get and extended 5 miles into Icy Strait.   
When the British explorer George Vancouver charted the area in 1795, the glacier had calved five miles into the newly created Glacier Bay.   John Muir visited in 1879 and in writings that inspired other visitors, described a Glacier Bay then 40 miles long.  
Today its 65 miles from the mouth of Glacier Bay to tidewater glaciers at the western end and those in the eastern arm known as Muir Inlet.  Many glaciers that recently calved into the sea, now end on land.  But as many glaciers retreat, a few are still advancing.  
We floated from the lush three hundred year old forests near the mouth of the Bay, with its spouting humpbacks, to the utterly barren rock faces of the upper reaches, newly scoured by tidewater glaciers, visited by the odd tufted puffin, we experienced the whole succession of geologic periods.   This speedy excursion through geologic history has left me feeling dreamy and speechless.  Hopefully a few pictures and an excerpt from  The Blue Bear will help create a vision for those who have not yet made this journey.
When a glacier retreats it begets rock as barren and bald as the moon…for a while – say ten or twenty years – life would remain an exceedingly small idea in this neighborhood; only lichens, moss, and a few other simple forms of life capable of grasping a a living from the minerals from the stones and the gases in the air are able to colonize such sterile rubble.  
In time however, the slow accumulation of organic material among the cracks and declivities would form something of a poor soil where seeds and spores borne in on the wind or clinging to the feet of birds would start to grow.  After a few spare pilgrims of grass and other flowering plants took root, more stingy soil would be formed, and after a half century or so, thickets of alder shrub would take the neighborhood by storm.  Alder contributes a rich detritus of rotting leaves and fixes nitrogen in the soil, enough so that after a few decades more, the seeds of [spruce] trees would begin to find their way in, take a firm grip, and send down roots to suckle at the soil.  If the seedlings survive, they rise into the light, exclaiming themselves above their bushy neighbors, until on a hot summer day a cloud of yellow pollen bursting from the ripened sex glands of distant kin drifts by on the wind and embraces the young tree.  Within days, seed cones clinging to its branches grow swollen, pregnant with the possibility of a forest.  Squirrels and jays move in, cutting, picking, eating, shitting, and scattering the gravid cones from hell to breakfast.  More seeds sprout nd more seedlings live, rising up to become saplings that eventually grow tall and large enough to touch branch tip to branch tip, casting a shadow over the alder, which then withers from the lack of light and dies.
Spruce needles are highly acidic, and for the next hundred years, those falling at the feet of the trees slowly alter the flavor of the soil from the alkaloid dullness of lime to a sharp bitter tang.  Ironically, spruce is acid-intolerant – it has no taste for its own waste – but hemlock and cedar are not.  These interlopers gradually mix and meddle with the hegemony of the spruce until they grow tall, rot and are thrown to the ground by fierce winter storms.  When spring comes, sunlight streaming through the resulting holes in the canopy ignites a riot of blueberry and dogwood.  After a gestation of centuries, a mature, proper forest is born.   

mouthThe term ice age usually brings to mind a situation continental in scale, and a period millions of years long that ended at the dawn of human history.   What’s cool about Glacier Bay, however, is that it’s a product of a much shorter era that fits squarely into our historical past and our human future.

Officially known as the Little Ice Age, it didn’t really get underway until the late 1600s.  At that time the Hoonah Tlingit people lived in a broad valley that was in the place of today’s Glacier Bay.   Then the glacier at the end of the valley started to move down it, driving the Hoonah Tlingit south across Icy Strait to Chicagof Island, where the good ship Aurora is in their care today.  By 1750 the glacier was as large as it would get and extended 5 miles into Icy Strait.   

Intermediate

When the British explorer George Vancouver charted the area in 1795, the glacier had calved five miles into the newly created Glacier Bay.   John Muir visited in 1879 and in writings that inspired other visitors, described a Glacier Bay then 40 miles long.  

Today its 65 miles from the mouth of Glacier Bay to tidewater glaciers at the western end and those in the eastern arm known as Muir Inlet.  Many glaciers that recently calved into the sea, now end on land.  But as many glaciers retreat, a few are still advancing.  

We floated from the lush three hundred year old forests near the mouth of the Bay, with its spouting humpbacks, to the utterly barren rock faces of the upper reaches, newly scoured by tidewater glaciers, visited by the odd tufted puffin, we experienced the whole succession of geologic periods.   This speedy excursion through geologic history has left me feeling dreamy and speechless.  Hopefully a few pictures and an excerpt from  The Blue Bear will help create a vision for those who have not yet made this journey.

next to upper

When a glacier retreats it begets rock as barren and bald as the moon…for a while – say ten or twenty years – life would remain an exceedingly small idea in this neighborhood; only lichens, moss, and a few other simple forms of life capable of grasping a a living from the minerals from the stones and the gases in the air are able to colonize such sterile rubble.  

In time however, the slow accumulation of organic material among the cracks and declivities would form something of a poor soil where seeds and spores borne in on the wind or clinging to the feet of birds would start to grow.  After a few spare pilgrims of grass and other flowering plants took root, more stingy soil would be formed, and after a half century or so, thickets of alder shrub would take the neighborhood by storm.  Alder contributes a rich detritus of rotting leaves and fixes nitrogen in the soil, enough so that after a few decades more, the seeds of [spruce] trees would begin to find their way in, take a firm grip, and send down roots to suckle at the soil.  If the seedlings survive, they rise into the light, exclaiming themselves above their bushy neighbors, until on a hot summer day a cloud of yellow pollen bursting from the ripened sex glands of distant kin drifts by on the wind and embraces the young tree.  Within days, seed cones clinging to its branches grow swollen, pregnant with the possibility of a forest.  Squirrels and jays move in, cutting, picking, eating, shitting, and scattering the gravid cones from hell to breakfast.  More seeds sprout and more seedlings live, rising up to become saplings that eventually grow tall and large enough to touch branch tip to branch tip, casting a shadow over the alder, which then withers from the lack of light and dies.

upperSpruce needles are highly acidic, and for the next hundred years, those falling at the feet of the trees slowly alter the flavor of the soil from the alkaloid dullness of lime to a sharp bitter tang.  Ironically, spruce is acid-intolerant – it has no taste for its own waste – but hemlock and cedar are not.  These interlopers gradually mix and meddle with the hegemony of the spruce until they grow tall, rot and are thrown to the ground by fierce winter storms.  When spring comes, sunlight streaming through the resulting holes in the canopy ignites a riot of blueberry and dogwood.  After a gestation of centuries, a mature, proper forest is born.   

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