Shamrock Mining Plan of Operations and Environmental Assessment Released for Public Review/Comment
The Park has released for public review the Shamrock Mining Plan of Operations and Environmental Assessment. The EA is available for public review and comment for one month. All comments must be submitted by July 3, 2013. More »
Chisana River Fire Grows, Creates 10,000 Foot Column
Due to continued hot and dry conditions, the Chisana River Fire grew from 2,900 acres to 7,718 acres June 17. More More »
Nabesna Road Geology
The first several miles of the Nabesna Road traverse relatively flat landscape underlain by accumulations of relatively young sediment. Much of this material is stream sediment, but a good deal of it, especially the beds of silt and fine sand, was deposited in huge glacial lakes which formed when glacial ice blocked off the stream valleys. Additionally, you will see many deposits of coarse gravel that were laid down by the glacial ice itself.
Mount Wrangell is the more distant, rounded and glacial covered dome southeast of Mount Sanford, with its summit of 14,163'. It is the park's only active volcano and occasionally steam plumes can be seen rising from its summit. Mount Wrangell's broad, gentle form is an excellent example of a shield volcano, in fact, it is the largest andesite shield volcano in North America. Stratovolcanoes form from thick, sticky, viscous lava that does not flow readily. Because of its thick nature, development of the volcano is through infrequent, but violent explosive eruptions. The resulting ash, cinders, and lava form steep slopes as they pile up. Shield volcanoes develop from more fluid lava. Because the lava flows more easily, shield volcanoes have more frequent, but less violent eruptions. These eruptions produce only limited amounts of ash and cinders, but large volumes of lava that flows into gentle slopes.
North of Mount Sanford and nearer to the road is the jagged prominence of Capital Mountain, with a summit elevation of 7,731'. The jagged dark colored ridge north and east of Mt. Wrangell is topped by 9,240' Tanada Peak. Capital Mountain and Tanada Peak are both remnants of once large shield volcanoes like Mount Wrangell, but their volcanic activity ceased and their summits have been heavily eroded and sculpted by the force of glaciers. Geologic studies and potassium-argon dating have indicated that the entire Tanada Peak shield volcano was formed between one and two million years ago and eroded to its present shape only during the last million years. On a clear day, Mount Jarvis can be seen over the right shoulder of Tanada Peak. It too is composed of lavas between one and two million years old, and its summit rises to 13,421 feet.
Flowing northward from the great ice fields of Mount Wrangell is the Copper Glacier. Its meltwaters give rise to the Copper River which flows northward off the mountains, and then westward along the end of the Wrangell Range. From there is turns southward and finally reaches Gulf of Alaska near Cordova. It is the only stream that cuts through the coastal barrier of the Chugach Mountains. Along much of its length, the Copper River marks the western boundary of Wrangell-St. Elias National Park and Preserve.
Watershed Divide. This is the highest point along the Nabesna Road with an elevation of 3,320'. Waters flowing west and south from here are carried into the Copper River and ultimately the Gulf of Alaska. Waters flowing easterly from here are carried by Jack Creek into the Nabesna River and on through the Tanana River to the Yukon River which empties into the Bering Sea.
Hiking the Skookum Volcano Trail
The Nabesna Mine went into production in the early 1930's and had produced over $1,870,000 in gold by the time that large scale mining ceased in 1940. Limited, small scale mining has continued since then. The mine entrance is on a very steep slope high up on White Mountain, so ore had to be transported hundreds of feet by aerial tramway down to the processing plant at the base of the mountain. The primary ore materials are gold-bearing pyrite and chalcopyrite which occur in limestone along with other metallic minerals such as magnetite, pyrrhotite, and pyrite. These mineral deposits probably formed when metal and quartz-rich fluids migrated from an underground chamber of molten material into nearby limestone where they cooled and solidified.
Continue on foot:
Approximately 1/3 mile past the parking area, a trail leads south towards the remains of the abandoned Rambler Mine, an area that was active after WWII, but never patented, and now part of the park. The trail is steep, but the effort rewards you with superlative views of the Nabesna River and Nutzotin Mountains.
Did You Know?
Vast, rugged, icy, and wild, Wrangell-St. Elias provides for lifetimes of discovery, reflection, recreation, and adventure.