Terrane Accretion in Southern Alaska
Lines with double arrows show approximate extent of National Park Service sites with respect to the various terranes. NP = National Park; NM = National Monument; NPres = National Preserve. The line of cross sec... More
Eruption of Mt. Redoubt - Public Domain image, National Parks Gallery
Lake Clark National Park, Mt. Redoubt. The eruption of Mt. Redoubt, an active volcano in Lake Clark National Park, illustrates how a volcano can pose an unexpected hazard in our modern age – and why monitoring ... More
Evidence for Tectonic Plates - Public Domain image, National Parks Gal...
The continents are blocks of thick crust that are passengers on the tops of large tectonic plates (lithosphere) that move over a softer part of Earth’s mantle (asthenosphere). Earthquakes, mountain building and... More
Lava Tube - geologic resources division
Entrance to Pua Poo Lava Tube. Public domain photograph of a cave, free to use, no copyright restrictions image - Picryl description
The Landscapes of Denali National Park Reveal Different Accreted Terra...
The highest mountain in North America, Denali (also known as Mt. McKinley), consists of granite that intruded through metamorphic rocks of older accreted terranes.
Landscapes of North Cascades National Park—Mt. Shuksan
At 9,127 feet (2,782 meters), Mt. Shuksan is the highest point in North Cascades National Park, Washington. The Alpine scenery is the result of rocks being shoved upward as terranes came crashing in.
Rift Zone Volcanic Features—Broken Top Volcano
Craters of the Moon National Monument, Idaho. Craters of the Moon National Monument lies along the Columbia Plateau–Yellowstone hotspot track, but recent volcanism is also due to Basin and Range continental rifting.
Beach Sediments—Gulf Islands - Public Domain image, National Parks Gal...
Gulf Islands National Seashore, Florida and Mississippi. The pure white sands of Gulf Islands National Seashore in Florida and Mississippi are grains of quartz derived from the Southern Appalachian Mountains.
Collapse Crater Formation—Magma Chamber
Magma accumulates in a chamber beneath a volcano as lava erupts through the summit and along fissures on the flanks. At times the magma inflates and erupts a large volume of material that partially empties the chamber.
Kilauea Volcano in Hawaii Volcanoes National Park—Labeled
Kilauea Volcano in Hawaii Volcanoes National Park has a large caldera on its summit. Smaller collapse craters are found on the floor and flanks of the caldera, including Halemaumau and Kilauea Iki. The Volcano ... More
San Andreas Fault—Pillow Basalt
Golden Gate National Recreation Area, California. Pillow basalt, formed as lava poured out on the ocean floor, was later scraped off the top of the subducting plate and thrust onto the edge of the continent.
Formation of Crater Lake—Deepest Lake in the World
The coating of volcanic materials sealed the bottom of the caldera. Over a few centuries rain and snowmelt partially filled the hole with the waters of Crater Lake. At 1,943 feet (592 meters), Crater Lake is th... More
Convergent Plate Boundary Development—Continental Collision (3 of 3)
Continents collide where subduction completely closes an ocean. The buoyant continental crust lifts up a broad region known as a collisional mountain range.
Formation of Crater Lake—Mt. Mazama
Mt. Mazama was a composite volcano up to 12,000 feet (3,700 meters) in elevation. Its magma chamber was filled with heavy (low-silica) magma in its lower part and lighter (high-silica) magma above. Paul Rockwoo... More
Volcanic Arc Features in Southern Alaska—Active Volcanoes
Lake Clark National Park, Redoubt Volcano. Public domain photograph of Alaska volcanic mountains, free to use, no copyright restrictions image - Picryl description
Carribean Tectonic Map - Public domain map
The Virgin Islands are in a broad zone where the landscape is being sheared up as the Carribean Plate slides eastward past the oceanic part of the North American Plate. Active volcanoes of the Lesser Antilles I... More
Hawaii Volcanoes National Park—Spatter Cones
Line of spatter cones forming during 1983 eruption of Kilauea Volcano.
Map of Tectonic Settings of NPS Sites
Map of the United States showing major plate tectonic settings and representative National Park System units within each setting.
![West Coast Tectonic Evolution—20 Million Years Ago [2 of 3]](https://cache.getarchive.net/Prod/thumb/cdn2/L3Bob3RvLzIwMTkvMDEvMDEvd2VzdC1jb2FzdC10ZWN0b25pYy1ldm9sdXRpb24yMC1taWxsaW9uLXllYXJzLWFnby0yLW9mLTMtMDdlMjc3LTEwMjQuanBn/40/41/webp "West Coast Tectonic Evolution—20 Million Years Ago [2 of 3]")
West Coast Tectonic Evolution—20 Million Years Ago [2 of 3]
As the mid-ocean ridge separating the Farallon and Pacific Plates entered the subduction zone, the Farallon Plate separated into the Juan de Fuca and Cocos Plates. A transform plate boundary developed where the... More
Collisional Mountain Range Development (1 of 3)
A plate capped by thin oceanic crust subducts beneath one capped by thick continental crust, forming an accretionary wedge and volcanic arc on the overriding plate.
Continental Rift Development—Plate with Thick Continental Crust
Continental crust is thick and buoyant, and therefore sticks up above sea level.
Formation of Crater Lake—High-Silica Eruptions
During the initial stages of its climactic eruption, the upper part of the magma chamber poured out ash, pumice, and rhyolite lava flows. Paul Rockwood painting, NPS.
Continental Rift Block Diagram - Public Domain image, National Parks G...
Basin and Range topography develops over a few million years as fault lines move gradually or more abruptly during tens of thousands of earthquakes. Lakes pond against active fault escarpments where one side of... More
Grocery Store Tectonics (1 of 5) Labeled
A grocery store checkout counter can be used to demonstrate the gradual growth of a continent via terrane accretion. The conveyer belt represents the oceanic plate subducting beneath the continental plate. The ... More
Evolution of Hawaiian Volcanoes
The Hawaiian Islands are only the tips of enormous shield volcanoes. Hawaii Volcanoes National Park on Hawaii lies directly above the hotspot and has high elevations and extensive volcanic activity. Haleakala N... More
DC Area Parks—Great Falls Park, Virginia.
Great Falls Park, Virginia. The rapids along the Potomac River occur where the water flows over the Fall Line, the abrupt boundary between hard metamorphic rocks of the Piedmont Province and soft sedimentary la... More
Ancient Passive Margin—Grand Canyon Supergroup
The region included the coastal plain as well as shallow water of the continental shelf. Rift valley strata from an earlier breakup of the continent are called the Grand Canyon Supergroup, whereas the igneous a... More
West Coast Tectonic Evolution—40 Million Years Ago
Forty million years ago, a large tectonic plate, known as the Farallon Plate, was between the Pacific and North American plates. Subduction of the Farallon Plate beneath the entire West Coast created a line of ... More
Ancient Subduction Zone - National Parks Gallery
Rocks found today along the San Andreas transform plate boundary originally formed in a subduction zone, when the ancient Farallon Plate dove beneath the edge of North America.
San Andreas Fault—Point Reyes National Seashore, California
The granite rocks are similar to those found in Yosemite National Park. They formed beneath ancient subduction zone volcanoes, were plucked from the edge of the North American Plate, and transported more than 3... More
Pahoehoe lava - geologic resources division
Pahoehoe lava has a smooth, ropey surface, formed when the lava is very hot and free-flowing. Hawaii Volcanoes National Park.
Hawaii—Emperor Hotspot Track - Public Domain image, National Parks Gal...
The islands get older, lower and smaller as they move away from the hotspot, which is currently located under Hawaii Volcanoes National Park. The submerged Hawaiian Ridge is old volcanoes that formed before the... More
Collisional Mountains—Hot Springs National Park, Arkansas, Hot Springs...
Hot Springs National Park, Arkansas. The mineral springs rise up in the center of the Ouachita Mountains, an extension of the Appalachian Mountains that surface in Arkansas and Oklahoma.
NPS Sites along Columbia Plateau – Yellowstone Hotspot Track
Shaded relief map of the Pacific Northwest highlighting National Park Service sites along the Yellowstone Hotspot track. Letters are abbreviations for NPS sites listed near the top of this page. The Yellowstone... More
Volcanic Arc Features in Southern Alaska—Collapse Calderas
Aniakchak National Monument Public domain photograph of a mountain range, national park, free to use, no copyright restrictions image - Picryl description
Collapse Crater Illustration - National Parks Gallery
A collapse crater (caldera) develops when the summit region of the volcano collapses as rubble into the emptied-out magma chamber. Lava flows and cinder cones can form during later eruptions on the caldera floor.
Continents Grow Outward by Terrane Accretion
In the digram, an oceanic island or continental fragment (incoming terrane) approaches a subduction zone, where it will eventually attach (accrete) to the edge of the continent. An active volcanic arc develops ... More
Yosemite Valley and Half Dome (Labeled)
Half Dome in Yosemite National Park is made of granite that solidified from magma tens of millions of years ago, when a subduction zone extended along the entire west coast. The overlying volcanoes have since e... More
Migration of Barrier Island—West Ship Island
West Ship Island in Gulf Islands National Seashore, Mississippi. The longshore current erodes sand from the “upstream” end of the island and deposits it on the other tip. Through the years, the island gradually... More
Mature Ocean Basin Diagram - Public Domain image, National Parks Galle...
The continents moved away from one another as parts of different tectonic plates. The transitions from thick continental to thin oceanic crust are passive continental margins because they are far away from the ... More
Rift Zone Volcanic Features—Capulin Volcano
Capulin Volcano National Monument, New Mexico. Capulin Volcano forms from volcanic activity associated with the nearby Rio Grande Rift. A road takes you to a spectacular view of the crater at the top of the cinder cone.
San Andreas Transform Plate Boundary
he Pacific Plate slides north-northwestward past the North American Plate along the San Andreas Transform Plate Boundary. The San Andreas Fault is responsible for most of the movement in western California, cau... More
San Andreas Fault—Tomales Bay (Labeled)
Point Reyes National Seashore, California. Tomales Bay is the surface expression of the San Andreas Fault. The granite rocks in the foreground are similar to those found in Yosemite National Park in the Sierra ... More
Big Island of Hawaii - Public Domain image, National Parks Gallery
The large shield volcanoes on Hawaii extend to almost 14,000 feet (4300 meters) above sea level. But the bases of the volcanoes lie about 18,000 feet (5500 meters) below sea level, on the floor of the Pacific Ocean.
Western U. S. Terrane Accretion
The yellow and green shows material added (accreted) to the western edge of North America during the past 200 million years. The North American Craton refers to the continent that existed prior to that time. Ro... More
Hard Lava Flows—Columbia Plateau Basalt
Columbia Plateau Basalt often forms columns that are ideally six-sided (hexagons).
Yellowstone Hotspot Track—Columbia Plateau, Oregon
Columns of basalt represent vast outpourings of fluid lava that covered large portions of Oregon, Washington, and Idaho as the hotspot surfaced 17 million years ago.
Tectonic Evolution of the Southern Appalachian Mountains—500 Million Y...
500 Million Years Ago—Iapetus Ocean Opens. Continental blocks destined to become North America and Gondwanaland drift apart. The eastern edge of ancient North America developed into a passive continental margin... More
Seafloor Coral—National Park of American Samoa
The floor of the Pacific Ocean is scarred with numerous tracks of islands, coral reefs, and submerged seamounts.
National Park Service Sites in Divergent Plate Boundaries
Shaded relief map of United States, highlighting National Park Service lands at Divergent Plate Boundaries. Letter codes are abbreviations for park names listed on Tectonic Settings pages linked below.
Paleogeographic Globe of the Late Triassic—217 Million Years Ago
The paleogeographic map shows that, during the Late Triassic Epoch, North America straddled the equator and Petrified Forest National Park (white dot on red map of Arizona) was at about 4° north latitude.
John Day Fossil Beds—Mural - Public Domain image, National Parks Galle...
One of the many outstanding murals at the Thomas Condon Visitor Center at John Day Fossil Beds National Monument depicts ancient life on the Columbia Plateau landscape. Note the columnar basalt columns in the foreground.
Earthquake and Volcanic Activity
Most earthquakes and volcanoes occur where the moving plates interact along their boundaries, and at hotspots.
Formation of Pillow Basalt—Illustration
As fluid basalt lava flows into the ocean it forms a pile of globular structures known as pillows.
Lava Surfaces—Aa Lava - Public Domain image, National Parks Gallery
Haleakala National Park Aa lava has sharp, angular blocks that develop when the lava is cooler and more sluggish.
Volcanic Arc Features in Southern Alaska—Crater Lake
Katmai National Park Public domain photograph by National Parks Administration, nature conservation, tourism, free to use, no copyright restrictions image - Picryl description
Continental Rift Development—Plate Rips Apart
As the plate stretches and thins, the underlying asthenosphere flows upward and expands like a hot-air balloon, lifting the region to higher elevations. The continental crust breaks along faults, forming long m... More
Colorado Plateau—Canyonlands National Park, Utah
Sedimentary layers of the ancient passive margin. As the Colorado Plateau rose upward, rivers carved downward, exposing those layers on the walls of canyons.
Emperor Hotspot Track - National Parks Gallery
The topography and bathymetry (underwater topography) of the northern Pacific Ocean reflect the movement of the Pacific Plate over the Hawaiian Hotspot. Prior to 42 million years ago, the Pacific Plate was movi... More
A Transported Volcanic Landscape—Pinnacles National Park
The pinnacles are the eroded remnants of hardened volcanic breccia—slurries of mud and rock from explosive eruptions.
Earthquakes and Coastal Landscapes—Redwood
Redwood National and State Parks, California. Visitors to Olympic National Park, Oregon Caves National Monument, or Redwood National and State Parks can look down and imagine the top of the Juan de Fuca Plate a... More
Collisional Mountains—Shenandoah National Park, Virginia.
Shenandoah National Park, Virginia. The rugged Appalachian Mountains are the eroded remnants of much higher mountains that formed as continents collided 300 million years ago.
Rift Zone Volcanic Features—Schonchin Butte
Lava Beds National Monument, California. The top of Sconchin Butte, a cinder cone, is a popular hiking destination along the main road through Lava Beds National Monument.
NPS Sites in Collisional Mountain Ranges
Shaded relief map of United States, highlighting National Park Service sites in Colisional Mountain Ranges. Letters are abbreviations for parks.
Continental Rift Zone—Grand Teton National Park
Grand Teton National Park, Wyoming. The east side of the Teton Range is a steep fault escarpment rising from the adjacent basin (Jackson Hole).
Big Bend National Park, Texas - Public Domain image, National Parks Ga...
The Marathon Mountains are the westernmost part of the ancient collisional mountain range that extends, in pieces, from the Maritime Provinces of Canada to west Texas.
Grand Canyon Strata - National Parks Gallery
The Colorado River has eroded through Paleozoic passive continental margin strata and older rocks, forming the Grand Canyon.
Convergent Plate Boundary Development—Terrane Accretion (2 of 3)
Oceanic islands and continental fragments approaching the subduction zone are too thick and buoyant to subduct. Instead, they attach to the edge of the continent as accreted terranes.
Haleakala National Park—vertical dike
A vertical dike was once magma that cooled and hardened on the flanks of Haleakala Volcano.
Petrified Forest Badlands - National Parks Gallery
Badlands area in Petrified Forest National Park. The Amazon-like landscape has evolved over more that 200 million years from a green tropical forest to red Painted Desert. Layers of the Late Triassic Chinle For... More
Hotspot Sites in the National Park System
The landscapes of National Park System sites along hotspot tracks differ depending on if the plate riding over the hotspot is capped by thin oceanic or thick continental crust. Oceanic Hotspots: Sites in Hawaii... More
NPS Sites Along Passive Continental Margins
shaded, raised relief map of north america Shaded relief map of United States, highlighting National Park Service sites along modern and ancient passive continental margins. Letters are abbreviations for parks.
Tourist Attraction - Beach Sediments—Dry Tortugas
Dry Tortugas National Park, Florida. The beaches of Dry Tortugas at the western end of the Florida Keys are fragments of shells broken up by wave action, and coral reefs developed in the shallow, warm waters.
Petrified Forest—Fossil Trees - Public Domain image, National Parks Ga...
Petrified logs along the Blue Mesa Trail. As the Colorado Plateau lifted upward, younger sedimentary layers eroded away, exposing the Chinle Formation, along with its colorful badlands, petrified logs, and othe... More
Development of Plate Tectonic Theory—Pangea
Blocks of thick continental crust fit together nicely along the edges of their shelves to form the supercontinent called Pangea.
Kilauea Volcano Caldera—Labeled
Kilauea Volcano in Hawaii Volcanoes National Park has a large caldera on its summit. Smaller collapse craters are found on the floor and flanks of the caldera, including Halemaumau and Kilauea Iki. The Volcano ... More
Formation of Crater Lake—Collapse Caldera
So much magma erupted that the upper part of the mountain collapsed into the void, forming the caldera. Paul Rockwood painting, NPS.
Tourist Attraction - Ouachita Mountains, Arkansas
The sandstone, shale and chert layers are part of a thick pile of sediments that were deformed and uplifted as Gondwanaland collided with the southern edge of ancient North America 280 million years ago.
Tectonic Evolution of the Southern Appalachian Mountains—750 Million Y...
750 Million Years Ago—Old Continent Rips Apart. The long mountain ranges and rift valleys were similar to those forming today in East Africa and the Basin and Range Province.
Hotspot—Lava Lamp Analogy - Public Domain image, National Parks Galler...
A hotspot is like the hot wax rising in a lava lamp. When the lamp is off, the cold wax is more dense than the oil. When you turn the lamp on the heated wax rises because it expands and becomes less dense than... More
Continental Rift Zone—Grand Teton National Park (Labeled)
Grand Teton National Park, Wyoming. The east side of the Teton Range is a steep fault escarpment rising from the adjacent basin (Jackson Hole).
Volcanic Sites in the Cascades—Crater Lake
Crater Lake National Park, Oregon. Crater Lake lies inside a caldera formed as Mt. Mazama violently exploded and collapsed 7,700 years ago.
Southern Alaska Subduction Zone
Plate convergence that built Alaska outward as a series of accreted terranes during the past 200 million years continues today. Kenai Fjords has oceanic sedimentary layers that have been metamorphosed, uplifted... More
Tectonic Evolution of the Brooks Range—200 Million Years Ago
200 Million Years Ago—Ocean separating northern Alaska and a continental fragment begins to close.
Tourist Attraction - Crater Lake (Labeled)
Crater Lake in Crater Lake National Park partially fills the large depression formed when a composite volcano erupted and collapsed in on itself 7,700 years ago.
Keweenawan Rift Features— Basalt Flow Rocks
Grooves on the basalt lava flow rocks in Keweenaw National Historical Park reveal the north-to-south direction that ice flowed across the region during the last ice age.
Layers in Grand Canyon National Park Tell a Plate-Tectonic Story—upper...
The upper portion of the canyon reveals continental shelf and coastal plain sedimentary layers of the ancient passive continental margin.
Yellowstone Hotspot Track—Yellowstone Plateau, Wyoming
Geysers, hot springs and other geothermal features in Yellowstone National Park (right) are reminders that the supervolcano that lies directly above the hotspot is still very much alive.
Columbia Plateau —Yellowstone Hotspot Track (1 of 3)
The Columbia Plateau and Steens Basalt are the initial surfacing of the giant plume head.
Tectonic Development of the Appalachian—Ouachita—Marathon Mountain Ran...
"Today"—Atlantic Ocean and Gulf of Mexico Open. The modern oceans originated about 200 million years ago when Europe, Africa and South America ripped away from North America. Fragments of the collision zone mou... More
Ocean Basin Opens - National Parks Gallery
If divergence continues, the continental crust completely breaks apart and thinner oceanic crust forms between the two continental blocks. The ocean basin sinks below sea level because the crust is thinner and... More
Development of Plate Tectonic Theory—Jigsaw Puzzle
The idea of continental drift, inspired by the observation that the continents fit together like picies of a giant jigsaw puzzle, provided strong evidence for the theory that later developed as plate tectonics.... More
Petrified Forest National Park and Continental Drift
The Petrified Forest region was probably similar to the meandering streams and forests of today’s Amazon Basin of South America.
Cascadia Subduction Zone—Topography, Earthquakes and Volcanic Eruption...
Subduction of the Juan de Fuca Plate results in the formation of the Coastal Ranges and Cascade Volcanoes, as well as a variety of earthquakes, in the Pacific Northwest. Olympic and Mt. Rainier national parks s... More
Illustration of the Evolution of Hawaiian Volcanoes
The Hawaiian Islands are only the tips of enormous shield volcanoes. Hawaii Volcanoes National Park on Hawaii lies directly above the hotspot and has high elevations and extensive volcanic activity. Haleakala N... More
Accreted Terrane—North Cascades National Park, Washington.
North Cascades National Park, Washington. The landscape is similar to Alaska. It consists of rocks that formed elsewhere, and then were deformed, metamorphosed, and accreted to North America.
Subduction Zone—Two Parallel Mountain Ranges
An accretionary wedge forms between the converging plates as material is scraped off the subducting plate. A forearc basin develops in the low area between the two mountain ranges. Farther inland, the subduct... More
Columbia Plateau —Yellowstone Hotspot Track (2 of 3)
When magma from the plume head reaches the surface, it flows across the surface as basalt.
Formation of Pillow Basalt - Public Domain image, National Parks Galle...
Pillow basalt layers formed more than a mile (1.6 kilometers) below the surface of the ocean are now almost a mile above sea-level on Hurricane Ridge Road in Olympic National Park, Washington.
Forming the Coast Range - Public Domain image, National Parks Gallery
Olympic National Park, Washington. Tilted layers of thick sandstone (pink) and thin shale (dark) along the coast at Olympic National Park reveal the enormous forces that lifted and deformed the oceanic layers a... More