Geologists delve into rock history in southeast Alaska (2023)

Geologists delve into rock history in southeast Alaska (1)

The mountains and valleys of the Alaskan Panhandle may seem static, but geologically speaking, the region is developing rapidly. KSTK interviewed a research geologist from the United States. Talk about the deepest history of the Southeast Geological Survey.

"Come on board," says geologist Peter Haeussler when he hears three sharp thuds on the deck of his 45-foot aluminum-hulled sailboat.Nice to meet you.It is Rangel's family mover.

His head looked out of the hatch amidships. Haeussler's friendly dog ​​Happy was part of the welcome committee but had to be carried up a narrow ladder to the main cabin.

Geologists delve into rock history in southeast Alaska (2)

Haeussler lives in Anchorage, but he's spent 30 years studying rocks in the Southeast. He received a Ph.D. His paper on the rock belt between Rangel and Juno, which he was "very interested in."

"I think the fascinating thing about geology is that I think you end up looking at the landscape of the world through a very different lens than a lot of other people," Haeussler said.

Those glasses are what Haeussler calls "deep time"—events on a scale that blur human life and even civilization.

"I think it's very easy for people to think about time in terms of what we know and experience," Haeussler explained, "which means, you know, 'It's spring, you know, and if winter passes, you know summer will be very hot."

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Human time spans pale in comparison to geological time, Haeussler said. To really understand geology, he said, you don't think in terms of decades or centuries, but thousands to millions of years.

"So when I look at the landscape around here," Haussler explained, "I'm often reminded of what it was like 20 to 25,000 years ago, when all these valleys were covered in ice and covered most of the mountains. top, think how different the world was back then or if you look at some of the ancient rocks in southeast alaska i mean it looks like most of southeast alaska is a piece of debris from somewhere else and trying to think about this process, probably about 400 million years ago, it came from a warm tropical environment. It was in the ocean. Very different."

Southeast Alaska is geologically unique, Haeussler said. The region's history is not so much part of a giant continent undergoing slow continental drift, but more of a smaller, more mobile part of the Earth's crust—think island regions like the South Pacific or around Japan.

What is now southeastern Alaska—known to geologists as the Alexander Formation—probably began at the equator. Based on the fossils here, that's at least as far back as geologists can think of.

"Then it moves around, and then it collides with other small chunks and clumps, and then it ends up really breaking up at the edge of North America, probably during the Cretaceous," Haeussler explained. "That must have been around the time of the large carnivorous dinosaurs, or a little bit earlier. Then it was probably a little bit south of this latitude, we don't know exactly how far, and then it cut off north along the North American border, so it stops here today. "

There's another particularly intriguing geological story in the far north of the Southeast—a crust born off the coasts of Oregon and Washington, cut along the edge of Alaska, next to the Yakutat region some 30 million years ago.

"That's why there are big mountains: the St. Elias Range in the Fairweather Range. It has a bigger impact in interior Alaska," Haeussler said. "We probably wouldn't see Denali in the Alaska Range without this large chunk of crust that juts into Alaska's southern edge."

This is not the only major land change factor in the region. Offshore is a fault system known as the Queen Charlotte-Fairweather fault. Haeussler said it is similar to the more famous San Andreas fault on the West Coast, but more active.

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"Queen Charlotte is like San Andreas in some ways, but it's like steroids: It moves faster. It's very sharp. It produces more big earthquakes in less time," "So it's a very impressive fault system," Haeussler said.

The Queen Charlotte-Fairweather fault is a strike-slip fault in which two tectonic plates move in opposite directions relative to each other. It moves at an astonishing rate of 5.3 centimeters per year -- about the length of a small lime. But compared to the San Andreas Fault, which moves about two-thirds of the distance each year—perhaps the length of a grape—that's pretty fast. Fast faults tend to produce more -- and bigger -- earthquakes, Haussler said.

The fault is visible just north of Freezing Point in Glacier Bay National Park. That's where the bugs walk on land -- while the rest are underwater.

"If you're on an Alaska Airlines flight from Juneau to Anchorage and it's clear weather, you can see this defect," Haussler said. Because it's moving."

The history of glaciers in the Southeast is also unique. There are tons and tons of ice above what is now the Inner Channel, and the land is pushed down as the outer coast curves up.

"Maybe it's kind of like, I don't know, if you had a fat uncle sitting next to you on the couch when you were a kid. But Ice Cap is kind of like that fat uncle sitting on something," Haeussler explained, "and then when you sit On the couch next to him, you get flipped up in the air because, you know, things happen, but there's another part of waiting, so when uncle gets up off the couch, then you go back.

Now that the glaciers have retreated significantly to the continent, the crust is returning, Haeussler said. What used to be shoreline near Wrangell is now hundreds of feet higher, and the ancient shoreline of the Outer Banks is slowly sinking.

Haeussler said he got into geology through climbing: "Then at some point I became interested in, what are these things that I'm stuck on? Then I also wanted to understand the landscape around [me]"

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Haeussler says geology first drew him to Alaska. He first attended geology field camp while a student at Michigan State University.

"This is my first visit to Alaska," he said, "I thought it was going to be a one-time thing, like it was a fun experience, [I wanted to] get out and do other things. But then a lot of us in Alaska Alaska Its claws are on you, and it won't let go."

While attending UC Santa Cruz, he suggested studying in the Southeast again.

"In my mind, I used to think of Alaska as more between Anchorage and Fairbanks than southeast Alaska," Haeussler said, "but when you look at the scientific problems that are worth looking at , Southeast Alaska is Alaska."

While residents of the Southeast typically can't stand by and watch rocks move, this has implications for communities living in geologically turbulent regions. For example, the fast-moving Queen Charlotte-Fairweather fault poses a significant potential seismic hazard to people living in the Southeast.

"For a neighborhood like Wrangell, it might not be that important to be some distance away, but if you're in Sitka or Elfin Cove, you're pretty close," Haeussler said. "The ground movement for something like this is building buildings. things that have to be taken into account when making things, and that sort of thing.”

But it's not just earthquakes that pose a potential hazard. Haeussler pointed to the 1958 earthquake on the Fairweather fault. It is probably best known for causing rockfalls in Lituya Bay, which hit the water and created a massive tsunami.

"It's still the world's tallest, world-record tsunami approach, rising 1,740 feet, splashing up hillsides and out of the bay," Haeussler said.

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Landslides, both on land and in water, can trigger massive tsunamis with potentially devastating consequences. Haeussler said most of the deaths from the 9.2-magnitude earthquake in Prince William Sound in 1964 were caused by tsunamis caused by underwater landslides, not by the quake itself.

Haeussler says work like his aims to mitigate hazards through things like earthquake hazard maps, which help determine where and how to measure new buildings.

"The danger is there anyway," Haeussler said, "so if you have an earthquake in the middle of nowhere and all these horrible things happen and no one's there, that's okay."

He said a good example happened recently: "An example in southeast Alaska, and in 2015 there was still aLarge landslide in the TaanfjordThen in October, it sank, hit the water, created the fourth largest tsunami wave ever recorded, and then it left the bay without anyone knowing it was happening. There is danger, but there is no danger because there is no one there. "

In addition to having his ship in Wrangell, Haeussler was in town to speak at the invitation of Sylvia Ettefagh, who organizes Wrangell's annual late-summer Bearfest celebration By. It's not bear season, but Ettefagh said Bearfest is trying to expand its educational and cultural offerings beyond the five-day festival.

"Part of the goal of Bearfest is education," Ettefagh explained. "It's part of our mission, to provide information so Wrangell can expand its knowledge base about the area it lives in. If you know how your area was formed and what the geology is like in your area, then geology is one of them. Part of it, you have a better understanding of where you live."

Haeussler said he plans to talk about the basics of plate tectonics and Alaska's geological history, as well as his recent research on earthquakes and tsunamis.

“I can say a lot, or I can answer almost anyone—try to answer every question that someone asks me,” Haeussler says with a laugh.

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When he presents his work to the public, he says, his goal is to give people a better understanding of how the geological world around us got to where it is today, and to create a sense of wonder about the epic story sense of the earth. in their own communities.


What is the geology of southeastern Alaska? ›

Southeastern Alaska is underlain by Quaternary surficial deposits and by sedimentary, volcanic, intrusive, and metamorphic rocks ranging in age from Quaternary to Proterozoic(?).

What is the history of geology in Alaska? ›

Most of Alaska's oldest rocks are approximately one billion years old, although Alaska's oldest known rock is about two billion years old. New earth materials are born from volcanoes, such as along the Aleutian Arc, recycled into sediments from weathering processes, and lithified from sediments into new rock.

What rocks are in southeast Alaska? ›

The dominant rocks in the sequence are interbedded andesitic tuff breccia, volcanic graywacke, and siltstone and argillite; less common rocks include coarse volcanic conglomerate, possibly broken pillow breccia, and dark blue-gray marble.

What is the oldest rock in Alaska? ›

The Iditarod rocks are more than 2 billion years old. This is remarkable because most rocks in Alaska formed 500 million years ago or even more recently. Earth formed about 4.5 billion years ago.

What are the major geographic features of Southeast Alaska? ›

Southeast Alaska includes over 1,100 islands, which are the tops of the partly submerged coastal mountain range. The region is bounded to the east by a mainland mountain range with peaks reaching 10,000 feet (3,048 m) in elevation. These mountains and associated icefields are bisected by several large glacial rivers.

What is the geology of Southcentral Alaska? ›

Most of the bedrock of Southcentral Alaska originated as marine sediments that were uplifted when terranes accreted onto the continent. Granite plutons have been exposed in the Talkeetna Mountains, Prince William Sound and in the Alaska Range.

What type of rock is found in Alaska? ›

Devonian rocks are widespread in southeastern Alaska. eastern Alaska consist of basalt, andesite, tuff, limestone, sandstone, slate, and conglomerate.

What are two historical events that happened in Alaska? ›

Alaska History
  • 1784 First white settlement was established on Kodiak Island by Gregory. ...
  • 1799 Shelikhov Russia American Company received the exclusive fur trading. ...
  • 1804 Tlingit Indians storm the fort and kill 408 of the 450 defenders.
  • 1867 The United States purchased Alaska from Russia for 7.2 million dollars.

What rock is Alaska known for? ›

Alaska doesn't have a state rock, but it does have a state gem, jade. A gem is a precious or semiprecious rock or mineral that looks pretty when it is cut and polished. Jade is usually green, and it is hard but easily carved. Most of the jade in Alaska is found on the Seward Peninsula.

Where are the oldest rocks in Alaska? ›

Geologist Tom Bundtzen uses a binocular microscope to look at one of the oldest rocks in Alaska, which formed more than 2 billion years ago and was found near Iditarod. Geologist Marti Miller with a 2-billion-year-old rock she collected near Iditarod.

Is it illegal to take rocks from Alaska? ›

You are prohibited from taking rocks, flowers, plants, fossils, horns, antlers, bones, and historical artifacts from Alaska State Parks. 11 AAC 12.170 (Disturbance of Natural Objects) prohibits removal or disturbance of natural objects.

What are the islands in southeast Alaska called? ›

The Alexander Archipelago (Russian: Архипелаг Александра) is a 300-mile (480 km) long archipelago (group of islands) in North America lying off the southeastern coast of Alaska. It contains about 1,100 islands, the tops of submerged coastal mountains that rise steeply from the Pacific Ocean.

What blue stone is only found in Alaska? ›

The Glacier Ice™ Gemstone with its deep blue coloration is reminiscent of Alaska's glaciers. Glacier Ice™ is a special variety of natural Blue Zircon available ONLY at Alaska Jewelry. Glaciers form when snow falls, accumulates, and does not melt.

Where is the oldest known rock on Earth? ›

The oldest intact rock found on Earth to date is from the Acasta Gneiss Complex of northwest Canada. U/Pb dates of zircon from the gneiss reach into the Hadean Eon at 4.02 Ga.

What is the pink rock from Alaska? ›


Rhodonite is a manganese silicate mineral known for its light-red or dark-pink hue.

What are 3 physical features of the Southeast? ›

The states in the upper part of the region have rolling hills, rich river valleys and high flat areas called plateaus. The states in the lower part of the region have beaches, swamps, and wetlands. The Appalachian Mountains cover most of the upper part of the Southeast region.

What is a fun fact about Southeast Alaska? ›

Southeast Alaska is composed of seven entire boroughs and two census areas, in addition to the portion of the Yakutat Borough lying east of 141° West longitude. Although it has only 6.14 percent of Alaska's land area, it is larger than the state of Maine, and almost as large as the state of Indiana.

What is considered Southeast Alaska? ›

Southeastern Area

Southeast Alaska covers an area about 500 miles in length from the U.S./Canada border just below Prince of Wales Island north to Yakutat and to Cape Suckling.

What is South Central Alaska known for? ›

Southcentral is a playground of Alaska activities, from legendary salmon fishing on the Kenai River and Copper River Valley to hiking in the Chugach National Forest to whale watching in Kenai Fjords National Park.

What are the geographic features of South Central Alaska? ›

South Central Alaska is home to a diversity of landscapes, including dense temperate rainforests, rocky beaches, and vast glaciers. Below treeline, particularly on the Kenai Peninsula and the other coastal areas within the region, forests of Sitka spruce, subalpine fir, and mountain hemlock abound.

What are the major settlements in South Central Alaska? ›

The major city is Anchorage. Other major towns include Palmer, Wasilla, Kenai, Soldotna, Homer, Seward, Valdez, and Cordova.

What 2 minerals were discovered in Alaska? ›

In addition to copper, the mines also produced a significant amount of silver. Today, gold is the primary metal mined in Southeast Alaska, although recent discoveries of silver, zinc, and lead in commercial quantities have led to new mines.

What rare stones are found in Alaska? ›

Alaska is blessed not only with record deposits of gold but also with an extensive variety of non-precious metal minerals and gemstones, a few of the most common include Alaskan jade, rhodonite, fluorite, garnet, cinnabar, and jasper.

What geological features are in Alaska? ›

Alaska's parks have active geologic features such as surging and retreating glaciers, simmering volcanoes, thawing permafrost, geological hazards (such as landslides), and fossils that tell us about the active geology of the past and present.

What are important history in Alaska? ›

The U.S. purchased Alaska from Russia in 1867. In the 1890s, gold rushes in Alaska and the nearby Yukon Territory brought thousands of miners and settlers to Alaska. Alaska was granted territorial status in 1912 by the United States of America.

What is Alaska famous for historically? ›

We are famous for the Iditarod, gold mining, sourdough, the Alaska Railroad, aviation, Alaska Native heritage, homesteading, world-class fishing and seafood, outdoor adventures, fresh air, and a slower, more self-sufficient way of life.”

What black stone comes from Alaska? ›

Hematite has also been called “Black Alaskan Diamond” although it is neither black nor a Diamond. However, “bloodstone” in North America refers to a dark green mineral with flecks of red in it (named because these red flecks look to some like splatters of blood).

What is the black stone in Alaska? ›

Blackstone Glacier starts at an elevation of about 5,000 feet (1,500 m) in the Kenai Mountains and flows generally north for 7 miles (11 km) and terminates at tidewater at the head of Blackstone Bay, about 87 miles (140 km) west-southwest of Valdez and 8 miles (13 km) south of Whittier, Alaska.

What is the black rock in Alaska? ›

Alaska, known for abundant wildlife, incredible fishing, stunning scenery, and of course oil, offers very little to the fluorescent world--at least so far.

When was the Stone Age in Alaska? ›

The oldest confirmed prehistoric sites in Alaska belong to the Eastern Beringian Tradition, dating from about 14,000 to 12,000 years ago.

What is the oldest rocks ever found in the United States? ›

Morton gneiss, also known as rainbow gneiss, is an Archean-age gneiss found in the Minnesota River Valley of southwestern Minnesota, United States. It is one of the oldest stones on Earth, at about 3.5 billion years old.

Where is the oldest rock in the US? ›

The really old rocks in America are found in Wyoming and the states around Minnesota. They date from the Paleoarchean Era and are more than 3 billion years old.

Can I take rocks from Yellowstone? ›

It is illegal to remove natural or cultural artifacts (plants, animals, bones, rocks, etc.) from the park.

What is rock collecting called? ›

Amateur geology or rock collecting (also referred to as rockhounding in the United States and Canada) is the non-professional study and hobby of collecting rocks and minerals or fossil specimens from the natural environment.

Can you sell rocks for money? ›

Sell to a Rock Shop

Ideally, if you found a local rock shop to do business with, this would be a great source of selling your collection. This is a very common way to sell rocks for part-time rock hunters. You can easily search for a local rock shop and establish a relationship.

Who owns Southeast Alaska? ›

Established in 1972 and celebrating over 50 years in business, Sealaska is the Alaska Native regional corporation for Southeast Alaska. Our 25,000 shareholders are Tlingit, Haida and Tsimshian people with more than 10,000 years of ancestral ties to the oceans, forests and communities of Southeast Alaska.

What is the largest city in southeastern Alaska? ›

The largest cities in the region are Juneau, Sitka, and Ketchikan. This region is also home to Hyder, the easternmost town in Alaska.

What is the most southern Alaskan city? ›

Adak is the southernmost community in Alaska and on the same latitude as Haida Gwaii in Canada, and Brussels, Belgium. It is less than three degrees of latitude north of the 49th parallel, which forms the western part of the land border between the Contiguous United States and Canada.

Are there rubies in Alaska? ›

Ruby is located on the south bank of the Yukon River. The village is on the western border of Nowitna National Wildlife Refuge and is one of two villages (Tanana is the other) that serve as staging points for expeditions into the 1,560,000-acre preserve.

Is there opal in Alaska? ›

JUNEAU, Alaska - A gemstone, billed as one of the largest gem-quality opals ever found, was sold for $143,750 at auction in Alaska on Sunday. The opal, dubbed the "Americus Australis," weighs more than 11,800 carats, according to the auction house Alaska Premier Auctions & Appraisals. It also has a long history.

What rock is turquoise with brown spots? ›

Limonite creates dark brown markings in turquoise, while sandstone creates tan markings. These markings are remnants of the host rock within the turquoise, and can resemble splotches or veins. They're called matrix.

What is the hardest rock on Earth? ›

Diamond is the hardest known mineral. It is a high-symmetry allotrope of carbon (C). It has a Mohs “scratch” hardness of 10, which makes it the hardest mineral.

What's the oldest thing on Earth? ›

Microscopic grains of dead stars are the oldest known material on the planet — older than the moon, Earth and the solar system itself. By examining chemical clues in a meteorite's mineral dust, researchers have determined the most ancient grains are 7 billion years old — about half as old as the universe.

Where did the rock older than Earth come from? ›

Bengaluru: A meteorite that landed in the Sahara Desert last year has been dated as being 4.56 billion years old, which makes the volcanic rock older than Earth, which is approximately 4.54 billion years old.

What is the white stone from Alaska? ›

Alaska White granite is a frosty blend of pale silver and frosty whites, marketed with warm neutrals and onyx hues. Imported from Brazil, this durable natural stone is available in a range of slab sizes.

Can you find amethyst in Alaska? ›

In Alaska, you can find amethyst crystals in the granite-rich uplands regions of Northway and Tok. You will generally find these amethysts as light pinkish-purple crystals either as parallel growing groups or single crystals.

What is the geological structure of Alaska? ›

Alaska's parks have active geologic features such as surging and retreating glaciers, simmering volcanoes, thawing permafrost, geological hazards (such as landslides), and fossils that tell us about the active geology of the past and present.

What landforms are in southern Alaska? ›

Rugged mountain summits, rounded mountain summits, and glacier landforms comprise the association.

What biome is southeast Alaska? ›

Southeast Alaska lies at the heart of the North American temperate rainforest — a forest that extends in a narrow 2,500-mile coastal strip from northern California, along coastal British Columbia, and to the eastern edge of the Kodiak archipelago in southcentral Alaska.

What faults are in southeast Alaska? ›

The Queen Charlotte-Fairweather fault in southeastern Alaska is analogous to California's San Andreas fault, both in length and type (strike-slip). Both faults form a boundary where two blocks of Earth's crust—the North American and Pacific tectonic plates—slide horizontally past each other in opposite directions.

What type of rock is Alaska Range? ›

It is mainly igneous rock granite. Denali's granite formed below the Earth's crust as part of a batholith.

What are some geographic features of Southcentral Alaska? ›

Southcentral Alaska contains several dormant and active volcanoes. The Wrangell Volcanoes are older, lie in the East, and include Mount Blackburn, Mount Bona, Mount Churchill, Mount Drum, Mount Gordon, Mount Jarvis, Mount Sanford, and Mount Wrangell.

What are the major settlements in Southcentral Alaska? ›

Southcentral Alaska
  • Anchorage Alaska. For many travelers Alaska begins in Anchorage. ...
  • Seward Alaska. Since its establishment in 1903, Seward has been one of Alaska's most important gateways. ...
  • Kenai Fjords National Park. ...
  • Talkeetna Alaska. ...
  • Homer Alaska. ...
  • Valdez Alaska. ...
  • Girdwood Alaska. ...
  • Palmer Alaska.

What is Southern Alaska called? ›

Southeast Alaska, often abbreviated to Southeast or Southeastern, and sometimes called the Alaska(n) Panhandle, is the southeastern portion of the U.S. state of Alaska, bordered to the east and north by the northern half of the Canadian province of British Columbia (and a small part the Yukon Territory).

What is Southeast Alaska's natural resources? ›

Alaska ranks among the top 10 areas in the world for the following minerals: coal, copper, lead, coal, zinc, and silver. Mining and minerals support an extremely lucrative part of the Alaskan economy - managed by the Department of Natural Resources.

What is the climate of Southeast Alaska? ›

The moist and mild climate of Southeast Alaska allows lush vegetation to flourish at high latitudes. Rainfall is abundant throughout the year, though April, May, and June mark a distinct dry season. The cloud cover and persistent rains of July mark the end of the dry season during a “typical summer” in Southeast.

What climate zone is Southeast Alaska in? ›

The climate in Juneau and the Southeast panhandle is a mid-latitude oceanic climate (Köppen climate classification Cfb) in the southern sections and an oceanic, marine subpolar climate (similar to Scotland, or Haida Gwaii), (Köppen Cfc) in the northern parts. Much of the southern parts are temperate rainforest.

What part of Alaska is uninhabitable? ›

Matthew Island. The small grouping of uninhabited islands is over 300 kilometers across the Bering Sea from the mainland, making it the most remote location in Alaska. Even after the bears were gone, the archipelago remained a difficult place for people.

Why are earthquakes in Southeast Alaska different from other parts of Alaska? ›

As the plate inches toward the northwest, it grinds past Southeast Alaska and British Columbia. Unlike the subduction zone, these faults slip primarily in a side-to-side motion, with a different tectonic plate on each side.


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