Tongass National Forest
| Local Links | ||
 |
Prince of Wales | |
|
Recreation | |
|
Conservation Education | |
|
Island Info | |
| |
Projects & Plans | |
|
Chugach National Forest |
|
Alaska Region |
|
Forest Service Headquarters |
|
Evaluate
Our Service We welcome your comments on our service and your suggestions for improvement. |
Tongass National Forest (907) 225-3101 e-mail comments to: |
|
The First Tunnel
As the tour winds its way into the cave, you'll see a basalt dike in the ceiling of the first passageway. This is an igneous intrusion into the limestone. Igneous rocks are formed by the cooling and consolidation of magmas which arise from a deep level of volcanic activity. The sharp, clean contacts between the limestone and the invading material of basalt are clearly visible.
The temperature of El Capitan Cave hovers around 40 degrees Fahrenheit
- the mean annual temperature of the region. In passages and chambers
far from the entrance, the temperature scarcely varies. Temperature fluctuations
of only several degrees have been recorded throughout the main passage.
Relative
humidity rarely falls below 80%. The cave is constantly damp and dripping
with water. As you hike into the cave you may notice
the small breeze blowing through the tunnel. The cave naturally breathes,
as air exchanges from the larger rooms farther into the cave and from
entrances further up the mountain.
The narrowest constriction in the cave is just before
the barrier gate. Here, just above your red helmet, condensation droplets
sparkle like diamonds. Temperatures from the phototropic (or entrance)
area are a bit warmer and converge with the temperatures from the inside
of the cave to form the shimmering water droplets.
Previous Page  |
Next Page
 |
USDA Forest Service - Tongass National Forest Accessibility Statement
Last Modified: July 11, 2007