{"id":7296,"date":"2021-07-19T10:21:07","date_gmt":"2021-07-19T17:21:07","guid":{"rendered":"https:\/\/jupitersway.com\/?p=7296"},"modified":"2021-07-25T18:33:56","modified_gmt":"2021-07-26T01:33:56","slug":"isostatic-rebound","status":"publish","type":"post","link":"https:\/\/jupitersway.com\/isostatic-rebound\/","title":{"rendered":"Isostatic Rebound"},"content":{"rendered":"\n

During 1794 George Vancouver, and his meticulous survey parties exploring Icy Strait, did not find Glacier Bay. It was filled with 4000 vertical feet of ice. <\/p>\n\n\n\n

\"\"
Leading edge of the Lamplugh <\/em>tidewater glacier<\/em>.<\/a><\/figcaption><\/figure>\n\n\n\n

Less than a century later, In 1879 John Muir entered and “discovered” Glacier Bay, describing a geology melting into the geography we might recognize today.<\/p>\n\n\n\n

Over 200 years the immense trunk glacier and most of the feeding glaciers were wasted at their bases by the warmer seawater and at their heights by the atmosphere. <\/p>\n\n\n\n

\"\"
A section of Reid Glacier’s leading edge, recently calved and exposing blue dense ice<\/a><\/em><\/figcaption><\/figure><\/div>\n\n\n\n

Not to be outdone by sea-level, in this region the land is rising<\/a>, fast. <\/p>\n\n\n\n

Relieved of the great weight of the rapidly melting ice, its mantle is lifting out of the underlying magma like a river barge unloaded of its cargo. Simultaneously the earth’s crust is decompressing like an unburdened memory-foam mattress. In Glacier Bay the uplift is causing land rise of almost an inch per year. <\/p>\n\n\n\n

This is geologic Isostatic Rebound.<\/p>\n\n\n\n

Entering Glacier Bay National Park on a five-day cruising permit, Jupiter travels north and backwards in time to a land that is scraped clean and newly exposed. <\/p>\n\n\n\n

At its southern entrance Glacier Bay has a similar prospect to the rest of Southeast Alaska, but traveling up bay you finally reach a glacial bulkhead in its dirty impermanence where recent recession of glaciers leaves a raw and poor landscape gradually and sparsely populated by indigenous flora and fauna. <\/p>\n\n\n\n

\"\"<\/a><\/figure><\/div>
\"\"<\/a><\/figure><\/div><\/div><\/div><\/div>\n\n\n\n

Relieved of its icy burden, the land receives a succession of vegetative species beginning with mosses and lichens. Pioneer plants such as fireweed and paintbrushes are followed by small shrubs, alders and cottonwoods. After 100-200 years coniferous forests will again prevail.<\/p>\n\n\n\n

\"\"<\/a><\/figure><\/div>
\"\"<\/a><\/figure><\/div><\/div><\/div><\/div>\n\n\n\n

Jupiter, anchored in the loom of Reid Glacier, enjoyed a pleasant afternoon and evening, until the glacier had other ideas.<\/em><\/p>\n\n\n\n

\n
\n
\"\"<\/a><\/figure><\/div>
\"\"<\/a><\/figure><\/div><\/div><\/div><\/div>\n\n\n\n

Bergie Bit aboard, nothing deters Jupiter’s natators from 34\u00ba water.<\/em><\/p>\n<\/div>\n<\/div>\n\n\n\n

Ambient temperature drops into the 40’s, sea temperature into the 30’s near ice. The unfamiliar scope of Glacier Bay confounds a sapient escapade. <\/p>\n\n\n\n

\"\"
Alice & Ky in front of the Reid Glacier whose upper surface is covered with cryoconite<\/a>.<\/em><\/figcaption><\/figure>\n\n\n\n

Jupiter’s crew logs more bears, more birds, more sea otters, sea lions, dolphin, whales, wolves, and freshly peeled rock in one week, than during any previous month of cruising.<\/p>\n\n\n\n