All Episodes

Learn Professor Wysession’s criteria for choosing more than 200 different geologic wonders in nearly 120 countries. Then explore the first on his list: the beautiful Greek island of Santorini, which is the relic of a volcanic eruption that had a profound effect on the ancient Mediterranean world.

Turn from eruptions to volcanoes themselves—in particular, Mount Fuji in Japan, a sacred site whose nearly perfect cone shape is a popular subject in Japanese art. Investigate the origin of volcanoes such as Mount Fuji and the special conditions that produce their sturdy symmetrical cones.

Continue your study of phenomena associated with plate tectonics by visiting the Galapagos Islands, made famous by Charles Darwin. This magnificent archipelago is on a volcanic hotspot near a mid-ocean ridge, formed by moving tectonic plates. Natural wonders abound in the region, both above and below water.

Visit the African Rift Valley, a mid-ocean ridge in the making. From the Red Sea to Mount Kilimanjaro, tectonic forces are splitting Africa apart, forming a new ocean in the process. This impressive valley is also the site of many fossil discoveries relating to early humans.

Zoom in on a remarkable feature of the African Rift Valley: the lava lake at Erta Ale in Ethiopia. This seething cauldron of molten rock is the oldest of the world’s five active lava lakes, and it replicates on a small scale the complex process of plate tectonics.

Chart the evolution of life revealed in the extraordinary fossils of the Burgess Shale in British Columbia. This mountainside quarry records the proliferation of new organisms—both familiar and bizarre—that followed a mass extinction half a billion years ago.

Read the incredible story told in the mile-deep layers of the Grand Canyon. Investigate the canyon’s formation and its connection to the opening of the Gulf of California and the birth of the San Andreas Fault. Also consider what gives the canyon its extraordinary visual effect.

What makes the highest mountains in the world so high? Follow the events that created Mount Everest and the rest of the Himalayan range on the vast Tibetan Plateau. Learn the role of the plateau in cooling the entire planet over the last 60 million years.

Much of the rock eroded from the Himalayas ends up in the Ganges River delta, one of the most biodiverse places on Earth. Learn how a delta forms and how the Ganges is both life-sustaining and destructive—qualities that give it a religious significance for millions of people.

The Amazon River collects rainfall from a huge region, called the Amazon basin. Trace the basin’s extensive network of tributaries, which produce 20% of the fresh water that flows into the ocean. Furthermore, the basin’s lush vegetation is responsible for 20% of all oxygen in the atmosphere.

Waterfalls are among nature’s most beautiful spectacles, and the most impressive falls form under unusual geological conditions. Along the border of Brazil and Argentina, tour thundering Iguazu Falls, a display of 275 separate falls over a 1.5-mile span with individual falls up to 270 feet high. Learn their close connection to a hotspot on the Mid-Atlantic Ridge.

Water doesn’t just flow on the surface; it also flows underground, carving caves in the process. The largest cave system in the world is Mammoth Cave National Park in Kentucky. Discover how groundwater excavated this network of passages that extends for at least 390 miles.

Focus on the spectacular shapes, such as stalagmites, stalactites, flowstones, and other cave features formed by minerals slowly precipitating from water. Then visit the recently discovered Cave of Crystals in Mexico, a science-fiction-like world with individual crystals up to 35 feet long.

Probe the mystery of the Great Blue Hole, an enormous submerged sinkhole ringed by a coral reef off the coast of Belize. Study the processes that create sinkholes, and investigate the nature of karst topography, which is produced by the erosion of limestone.

The picturesque limestone islands in Vietnam’s Ha Long Bay are an example of mature karst topography. Discover how the bay’s cone-shaped towers are related to the sinkholes in Lecture 14. The key to understanding their puzzling geology is to focus not on the rock that’s there, but what’s missing.

Continue your study of erosional features with Utah’s Bryce Canyon, the densest display of weathered rock pinnacles, called hoodoos, anywhere in the world. Learn that Bryce Canyon isn’t really a canyon because it hasn’t been formed by a river. But then what created the hoodoos?

Go to Uluru-Kata Tjuta National Park in Australia to inspect two popular attractions shaped by erosion: Ayres Rock, known locally as Uluru, and the Kata Tjuta rock domes. Trace the history of moving plates, rising and receding seas, and constant weathering that created these impressive structures.

Famous as the landing pad for aliens in the movie Close Encounters of the Third Kind, Devils Tower in Wyoming is an otherworldly geological formation. Discover how this massive tower of igneous columns developed. Along the way, investigate why nature loves hexagons.

Head south to a pristine, unearthly continent: Antarctica. Explore the varied geology and the complex behavior of the giant ice sheets that flow relentlessly toward the ocean. Among its attractions, Antarctica is a superb place to test techniques for exploring cold, dry environments such as Mars.

Witness the power of glaciers, which carry a continuous stream of ice and rock from the tops of mountain ranges down to the base—often to the sea, such as at Columbia Glacier in Alaska. Chart the rapid retreat of Columbia Glacier since 1980, which has been triggered by climate change.

Visit the stunning fjords of Fiordland National Park in New Zealand, focusing on the most famous of these flooded glacial valleys, Milford Sound. The drama of the landscape is matched by tumultuous tectonic forces that are slowly ripping New Zealand apart.

The Rock of Gibraltar marks the gateway from the Mediterranean Sea into the Atlantic Ocean—a connection that has been closed on and off through recent geologic time. Explore the currents, catastrophic floods, and drastic sea-level changes that have occurred at the strait of Gibraltar and throughout the Mediterranean basin.

Why are the tides in Canada’s Bay of Fundy exceptionally high? Probe the principles of tides—what causes them, why the times of high and low tide vary from day to day, and the peculiar geometry between Nova Scotia and New Brunswick that results in an extraordinary tidal range.

The Hawaiian Islands are part of the Hawaiian-Emperor Seamount Chain, which stretches 3,600 miles across the western Pacific Ocean. This feature is mostly straight, except for a curious sharp bend. Investigate the origin of the chain and the special qualities of its easternmost element: the big island of Hawaii.

What happens when a hotspot is beneath a continent? The answer is Yellowstone National Park, a wonderland of geysers and hot springs nestled in the gigantic caldera of a supervolcano. Tour the attractions of Yellowstone, and ponder the history and future of the hotspot that fuels it.

Imagine a place where steam is so acidic that it burns your lungs, where flaming, liquid sulfur condenses from that steam, and a turquoise-colored lake is filled with the equivalent of battery acid. This hellish place is the crater lake of Kawah Ijen on the island of Java in Indonesia.

Visit Iceland, a geologist’s paradise where you can walk along the Mid-Atlantic Ridge. Iceland is a hotspot that sits atop the plate boundary that divides North and South America from Europe and Africa. Here, volcanoes and glaciers—fire and ice—coexist.

Home to some of the world’s most beautiful beaches, the Maldives in the Indian Ocean show the tranquil end-stage of ocean islands built on hotspots. The volcanoes beneath this coral reef archipelago are long since dormant, and the islands themselves barely rise above sea level.

Begin a series of lectures on desert regions by exploring the Dead Sea. Learn why this body of water on the border between Israel and Jordan is almost nine times saltier than the ocean and has the lowest elevation of any place on Earth.

Travel to the world’s largest salt flat, Salar de Uyuni in Bolivia. Almost the size of Connecticut, Uyuni is the flattest place on the planet. When it gets a very thin layer of water, it becomes the world’s largest mirror. Uyuni contains the world’s largest reserve of lithium—should it be mined?

Contrast two of the world’s most fascinating deserts, the Namib and Kalahari deserts in southern Africa. The Atlantic shoreline of the Namib Desert has been aptly named the Skeleton Coast. The Kalahari Desert includes the mighty Okavango River, which empties into the arid landscape and then disappears.

Located in the eastern Sahara Desert, Siwa is an island of water in a giant sea of sand. Investigate how an oasis with 1,000 springs can exist in one of the driest places on Earth. One clue is that the water beneath Siwa soaked into the ground more than 20 million years ago.

Investigate a stunning atmospheric phenomenon caused by events both inside Earth and in outer space. The shimmering colors of auroras result when particles from the solar wind are accelerated in Earth’s magnetic field, which is generated by Earth’s churning iron core.

Meteor Crater in Arizona is the best preserved of Earth’s few remaining impact craters. Why does the moon have more than 500,000 craters at least as large? Explore what happens when extraterrestrial debris strikes Earth at escape-velocity speeds. A relatively small object can do a surprising amount of damage.

In an entertaining change of pace, watch a countdown of 10 geological wonders that are hard to classify, from number 10—the White Cliffs of Dover—to number 1—a geological mystery in Death Valley that would seem like a hoax if it weren’t true.

Tour some of the amazing geological features beyond Earth, among them planet-circling lava flows on Venus and the solar system’s largest volcano and canyon on Mars. Close with the hydrocarbon lakes on Saturn’s moon Titan, proving that there is no end to geological wonders throughout the cosmos.