Castle Crags State Park

Geologic History

Castle Crags State Park is within the Klamath Mountains geomorphic province. The eastern Klamath Mountains are built from the oldest rock in the range with the newest to the west. This is due to the continued accretions of oceanic crust added on to the western edge of North American continent. Rocks surrounding Castle Crags are mostly of the Ordovician-aged (443–490 million year old) Trinity ultramafic sheet.

Castle Crags State Park
The dramatic granite of Castle Crags State Park is the result of a plutonic intrusion that is 160 million years old..

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Marine Terraces of California

In 2012 I first visited the marine terraces of coastal Mendocino County and was captivated by what I learned. The blog and graphic I cooked up after that visit has been one of the more popular entries on this website. In fact, the United States Geological Survey recently published a document on the Marine Terraces of California that features:

  • How marine terraces form
  • Soils sequences of California’s terraces
  • Where to find marine terraces of California
  • The main graphic from my blog about Mendocino’s ecological staircases

Marine Terraces of California
Marine Terraces of California

Find the document here:

Schulz, M., Lawrence, C., Muhs, D., Prentice, C., and Flanagan, S., 2018, Landscapes from the waves—Marine terraces of California: U.S. Geological Survey Fact Sheet 2018–3002, 4 p.

Middle Tennessee Cedar Glades

Map adapted from William J. Wolfe, “Hydrology and Tree-Distribution Patterns of Karst Wetlands at Arnold engineering Development Center,” USGS

Edaphic islands have long-fascinated me–especially having grown to understand the serpentine barrens of the Klamath Mountains. So when we found ourselves visiting the Central Basin Region of middle Tennessee I discovered, through the help of the Tennessee Native Plant Society, that this area is botanically special for its limestone prairies, often called glades. While numerous state designated natural areas were recommended, I chose to learn about the Middle Tennessee Cedar Glades at Flat Rock Glades and Barrens State Natural Area.

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Rarities and Ramblings • Horse Mountain Botanical Area: Six Rivers National Forest

Original Publication DATE: 2/14/2010 3:14:00 PM

Venturing east on Highway 299 from Humboldt Bay, a stark transition–rarely noticed by travelers–occurs at Berry Summit (2900 ft). Leaving the Coast Range and entering the Klamath Mountains the landscape becomes defined by varied, complex rock types. One of these unusual rock types is known as ultramafic rock or more commonly as Serpentine. In North America, serpentine rock appears at the Earth’s surface most frequently in northwest California. The Horse Mountain Botanical Area (HMBA) is a celebration of the rock and climate that interact to create unique high elevation plant communities. In coastal northwest California, spring has arrived. Allison and I did not want winter to pass us by–we were ready for some snow play. Packing our snowshoes and lunch, we drove to the snow of the HMBA in the Klamath Mountains in less than an hour.

Above is an map of the location of the Horse Mountain Botanical Area in the Six Rivers National Forest.
Above is an map of the location of the Horse Mountain Botanical Area in the Six Rivers National Forest.

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Limestone Ridge ~ Trinity Alps Wilderness

Original Publication DATE: 10/12/2009 2:23:00 AM

Gaining an understanding of geology and fire ecology

I had often pondered a high and extensive ridgeline in the middle of the Trinity Alps Wilderness from other mountain top vantage points on which I stood–at one point or another–in my adventures in the Klamath Mountains. It took me several years to realize this jagged range had its own name and many years more to actually get to this isolated place. Finally, in October, I climbed my way into the high country known as Limestone Ridge. I had read this extensive ridgeline (over 3 miles long) was one of the best examples of Karst topography in western North America. This summer, the spectacular Marble Mountain was my first introduction to Karst limestone landscape in the Klamath so I assiduously pursued a chance to see more. With those distant images and arresting words burned on my brain I was finally climbing–up–up–up–from Hobo Gulch in the Trinity River Canyon.

Limestone Ridge
Climbing higher and higher, smoke lingers from this years fires while charred chaparral and montane forest remind the temporal visitor of previous year’s fires–leaving the gabbro pluton exposed, as if only just uplifted from the depths of the earth.

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