Why are there so many hills in San Francisco?

Any visitor to San Francisco will be impressed by the number of hills and how they contribute to the overall beauty of the city. People (like me) who have resided in San Francisco have found biking and walking routes to avoid the steepest hills, and have appreciated how the hills compartmentalize the city into distinctive neighborhoods and provide stunning views....

Plate tectonics 101—what happens when plates move toward each other?

When plates move away from each other (divergent boundaries; see last post on December 31), new oceanic crust is created. Since Earth is not expanding, ocean crust must be destroyed elsewhere. This happens at convergent boundaries, where plates move toward each other. Here, oceanic crust is destroyed, or rather, it gets recycled back into Earth's depths. The places where oceanic...

The geology of Yosemite National Park

With stunning vistas of shear rock walls, cascading waterfalls, rounded granite domes and jagged spires, it's no surprise that Yosemite is one of the most popular national parks in the U.S. While most visitors are drawn to Yosemite Valley, the park has numerous other wonders beyond the valley and even the park boundaries in the Sierra Nevada (=snowy mountain range...

The Geology of Crater Lake National Park

Like most of our national parks, the spectacular beauty of Oregon's only national park is a result of the geologic processes that created it. But whereas most of our parks were created by gradual processes over long periods of time—for example, erosion by the Colorado River to create the Grand Canyon—Crater Lake was created in a few days during a...

South Sister—the third highest volcano in Oregon and one of its youngest

The Three Sisters volcanoes, located in the Three Sisters Wilderness west of Bend, Oregon, are part of the Cascade Range of volcanoes formed above the Cascadia subduction zone. "For magnificence of glacial scenery, for wealth of recent lavas, and for graphic examples of dissected volcanoes, no part of this range surpasses the area embracing the Sisters and McKenzie Pass", said...

How does the Rogue Valley fit into the larger tectonic picture?

In the last three posts, we explored the geologic makeup of the Rogue Valley region. Most people know that there is a subduction zone off the coast of the Pacific NW and you might wonder: how does the Rogue Valley region fit into this larger picture? We will explore the tectonic setting in this post. This diagram shows the present...

The Rogue Valley region in SW Oregon: displaying 300 million years of geologic time

Typically, I post blogs when traveling away from my home in Ashland, Oregon. But with COVID-19 keeping us all at home, it seems a good time to investigate the landscape of my local region. Ashland is a tourist town best known as the home of the Oregon Shakespeare Festival (OSF), an eight-month season of 11 plays—four by Shakespeare and seven...

About the Blogger

Karen (here with Mt. Shasta in background) is a geology professor emerita who aims to provide a "pocket geologist" for world travelers. Follow the blog to explore the landscapes of our planet and figure out what causes them to look the way they do.

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