Watch Doug's Geology Journal 3s38m

In the Red Rock country of Utah and Arizona the earth's crust has been pushed up by the collision of two massive tectonic plates, lifting the land in one large block. Doug marvels at how the forces of erosion have worked on that block for eons, sculpting some of the world's most famous rock formations, including pinnacles, slot canyons, buttes, arches, and the incomparable Grand Canyon.

Sicily is an island of two crashing tectonic plates and one very active volcano. Doug climbs the erupting Mount Etna and roams Sicily's gorgeous rocky coast and the captivating hill towns and geoparks inland. From the bottom of the sea the two colliding tectonic plates have pushed up limestone, a rock used for art and architecture by the many cultures that have mingled here over the millenia.

In the Basin and Range geologic province of the western United States, Doug explores California's Death Valley and remote hidden places in Nevada where few people have ever been. The Basin and Range is where the earth's crust has been raised up and slowly stretched and broken apart into parallel blocks of rock, creating a repeating series of rugged mountain ranges with valleys between them.

Doug is well acquainted with California's infamous San Andreas Fault, having lived on top of it for many years. He travels the fault's trace, from the Salton Sea in southern California, past San Francisco and toward Point Arena on the Pacific coast. Movement on the fault has shoved rock formations hundreds of miles and forged mountain ranges and has even helped create majestic redwood forests.

A volcano is going off in Iceland, and Doug gets there fast. The volcano's lava contains rare material from the beginning of Earth's 4.5-billion-year history. Iceland is defined by its geology, and Doug relishes giant waterfalls roaring over ancient lava flows; ice caps, icebergs, glaciers, and geysers; and how the island is split down the middle by the parting of two massive tectonic plates.