Saturday, July 11, 2015

Spelunking in Alaska!

Leonard, John, and Java
From Coffman Cove we made our way into Ketchikan to await the arrival of John, our Nephew, who flew in to spend a few days with us aboard Got d' Fever.  We were delighted to have his company and planned some fun excursions despite the clouds and rain.  We motored from Ketchikan to Thorne Bay where we toured El Capitan Cave.  Cave exploration or spelunking is definitely not the first thing that comes to mind when you think of Alaska.  
Steep Stairs to the Top
There are actually 500 caves on Prince of Wales Island, the largest being El Capitan with over two miles of passageways; El Capitan was only recently discovered by loggers in the mid-1990’s.  We rented a car in Thorne Bay and drove to the northern end of the Island where we met our U.S. Forest Service tour guides.  It became clear why these caves had not been discovered earlier by modern man, a steep staircase of 370 steps have been constructed by the Forest Service in order to reach the top of a cliff where the cave entrance is found.  
Cave Entrance
With our hardhats and headlamps, we moved into the darkness, squeezing between boulders and low ceilings before entering into a large room, and then another, and another.  Our guide pointed out mineral deposits, generally composed of calcium carbonate that dissolved from the surrounding limestone by water. 
Mineral Deposits
The water’s capacity to hold calcite is diminished when met with air in the cave and causes the calcite to be deposited, creating various unique formations.  At one point in the tour, we turned off our headlamps and stood still in the blackness, listening to the drip, drip, drip of water that has taken place over thousands of years.  
Walking through the Caves, El Capitan
Millions of years ago, the cave was once a reef, but now lies 360 feet above sea level, marine fossils have been found in several places within El Capitan Cave.  Other discoveries include the excavation of bear skeletons found in various passageways; carbon dating indicates the bones to be over 11,000 years old suggesting that the El Capitan valley was free of glacier ice at that time.  
Karst Sinkhole/Shaft
These discoveries have spawned more research into the prehistory of the southern portion of Southeast Alaska.  On our drive back to Thorne Bay, we stopped at Beaver Falls Interpretive Trail, a system of boardwalks through Karst formations.  Karst is a landform shaped by the dissolving action of water on carbonate bedrock.  
Karst Falls
Karsts include features like spires and pinnacles above ground as well as sinkholes, shafts, and disappearing streams and caves below ground which develop over many thousands of years.  On our walk, we saw sinkholes, shafts, and a waterfall all part of this karsk area.  It was a nice day’s outing despite the pouring rain and we kept dry in our rain gear, the official uniform of Alaska.

Boardwalks through the Karst Area

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