Geology
Natural Features & Ecosystems
Natural Features & Ecosystems
Aniakchak Caldera is a raw and rugged volcanic feature laying in a landscape that is, because of its remoteness, little affected by human occupancy. Plant and animal communities are in tune with the natural phenomena that control their habitat. Volcanic activity has subsided since the last eruption in 1931, but the geologic processes that follow such activity continue to weather, erode, and redistribute the volcanic materials. Hot spots and warm springs on the caldera floor indicate that eruptive activity may resume at any time.
Nature & Science
Nature & Science
Midway down the wild and roadless Alaska Peninsula lies one of the Nation's most fascinating recent volcanic features. Aniakchak is a 6-mile-wide, 2,000-foot-deep caldera formed by the collapse of a 7,000-foot mountain. Lying inland in a region of frequent clouds and stormy weather, Aniakchak remained unknown to all but native inhabitants until the 1920s.
Then, geographers remotely plotting mountain locations along the caldera's rim noticed their circular configuration. Eventually, in 1922, a geologic field party gazed down into the caldera. They brought back news of Aniakchak's immense proportions. Although a dozen calderas stand on the Alaska Peninsula, Aniakchak ranks among the largest. Its fascinating volcanic history can be read from its exposed internal plumbing.
About 3,500 years ago, a dramatic explosion caused the loss of some 3,000 feet of the upper mountain. The remainder of the mountain next collapsed, leaving a relatively flat-floored, ash-filled bowl. Since the caldera first formed, many lesser eruptions have created the small cinder cones, lava flows, and explosion pits dotting its floor today. Wave-carved terraces high on the caldera wall indicate that the caldera once contained a deep snow-fed lake, much like Crater Lake in Southern Oregon. However, hydraulic pressure or overflow eventually led to a breech of the caldera wall at a weak or low point. The result was a massive flood that created the great cleft through the caldera wall now known as The Gates. The Gates now allows the Aniakchak River to begin its tumultuous 27-mile course southeastward to the Pacific Ocean.
Aniakchak's most recent volcanic activity came in 1931. A small but impressive explosion pit was added to the pockmarked caldera floor that year. Many thousands of tons of ash lay strewn within the caldera and scattered up to 40 miles away over the small villages. Fortunately, this volcanic episode was documented both before and after by an indomitable geologist and Jesuit priest, Father Bernard Hubbard. His photographs and descriptions provide an important benchmark for judging the likely rate of recovery of vegetation to the devastated caldera. Mosses, grasses, and more complex flowering plants have invaded sheltered spots. Brown bear and caribou have returned. Spawning runs of sockeye salmon now fight their way up the Aniakchak River and into Surprise Lake, the river's shallow headwater lake inside the caldera.
In creating Aniakchak National Monument and Preserve, Congress recognized the unique geological significance of the caldera and also acknowledged the outstanding wildlife and recreational values of the Aniakchak River by designating it a wild river within the National Wild and Scenic Rivers System. The parklands boundaries also contain other important resources. West of the caldera lies the waterfowl and migratory bird habitat of Bristol Bay's coastal plain. To the east, rugged bays and inlets of the Pacific coast and offshore islands provide habitat for sea mammals and sea birds. Evidence of ancient human presence at Aniakchak is minimal. However, more may one day be known of this important transition zone between ancestral Aleuts and Yupik-speaking people.
Aniakchak In Depth
News from the Parks
Colorado Section of Vast Bike Network is 1,000 Miles
January 5, 2009 - 12:43pm
More than 1,000 miles of the 50,000-mile bikeway being spliced together throughout North American lies in Colorado. The Colorado portion is part of the Great Parks section, which includes 2,518 miles from Jasper National Park in Alberta, Canada, to Mesa Verde National Park outside of Durango.
January 5, 2009 - 12:43pm
More than 1,000 miles of the 50,000-mile bikeway being spliced together throughout North American lies in Colorado. The Colorado portion is part of the Great Parks section, which includes 2,518 miles from Jasper National Park in Alberta, Canada, to Mesa Verde National Park outside of Durango.
Ranchers Oppose Yellowstone Bison Relocation
January 5, 2009 - 12:32pm
Ranchers are voicing concern about plans to relocate some Yellowstone Park bison to Indian reservations in Montana and Wyoming. The ranchers are worried about the animals' history of carrying brucellosis, a disease that causes domestic cows to miscarry.
January 5, 2009 - 12:32pm
Ranchers are voicing concern about plans to relocate some Yellowstone Park bison to Indian reservations in Montana and Wyoming. The ranchers are worried about the animals' history of carrying brucellosis, a disease that causes domestic cows to miscarry.
A Trip to Yosemite National Park via YARTS is a Must for Valley Residents
January 5, 2009 - 12:31pm
The YARTS bus sped up Highway 140 from Merced into the foothills. It passed Mariposa and stopped at the entrance to Yosemite National Park. A sign read, “Chains required.” The driver parked, and deftly fitted the chains over the tires. A horde of enthused travelers lined up outside the bus, but there were no more seats. Instead of turning them away, the kindly driver allowed them to board the bus and stand in the aisle for the remaining 13 miles of the trip.
January 5, 2009 - 12:31pm
The YARTS bus sped up Highway 140 from Merced into the foothills. It passed Mariposa and stopped at the entrance to Yosemite National Park. A sign read, “Chains required.” The driver parked, and deftly fitted the chains over the tires. A horde of enthused travelers lined up outside the bus, but there were no more seats. Instead of turning them away, the kindly driver allowed them to board the bus and stand in the aisle for the remaining 13 miles of the trip.
Nene Killed on the Road in Haleakala National Park
January 5, 2009 - 12:21pm
An adult nene was killed on the road at Haleakala National Park on Dec. 28. Motorists traveling to the park are asked to drive slowly and cautiously. Visitors reported the dead nene to Visitor Use Assistant Tony Manion at 7:30 a.m. Park Ranger Chad Riggin retrieved the dead nene from the road near mile marker 16.
January 5, 2009 - 12:21pm
An adult nene was killed on the road at Haleakala National Park on Dec. 28. Motorists traveling to the park are asked to drive slowly and cautiously. Visitors reported the dead nene to Visitor Use Assistant Tony Manion at 7:30 a.m. Park Ranger Chad Riggin retrieved the dead nene from the road near mile marker 16.
Life's a Beach: U.S. Virgin Islands are Calling You
January 5, 2009 - 12:19pm
Don't just sit there. Pick a destination and plan a vacation, maybe to someplace a little exotic, where national parks come with tropical beaches, and boats rather than big RVs are a common mode of transportation. You can enjoy all that without fretting over currency exchange rates or making sure that your passport is up to date if you head to a little paradise called the U.S. Virgin Islands.
January 5, 2009 - 12:19pm
Don't just sit there. Pick a destination and plan a vacation, maybe to someplace a little exotic, where national parks come with tropical beaches, and boats rather than big RVs are a common mode of transportation. You can enjoy all that without fretting over currency exchange rates or making sure that your passport is up to date if you head to a little paradise called the U.S. Virgin Islands.
