Between Lake Almanor’s southern reign in California and the northern tip of Oregon's Crater Lake, lies a region steeped in a rich history of fire and ice. Where geology and history have collided from the depth of a disrupted and eruptive past, amazing landscapes remain. On a 500 mile, two-state journey--encompassing National Parks, State Parks, and Wildlife Refuges--the Volcanic Legacy Scenic Byway (The Byway) provides a lens into these landscapes and an opportunity to learn how history shaped them and the communities which surround them.
Beginning on the southern end of The Byway, Lake Almanor sits at the boundary of the Cascade and Sierra Nevada geologic provinces, south of Lassen Peak. The faulting that formed the Sierra Nevada range also created a valley where the lake currently resides. According to Kurt Sable of the Lassen National Forest, “It is presumed a pre-existing lake sat in the valley, and was then filled in with sediment to form a meadow. The meadow was then dammed to form the present Lake Almanor.”
Sable also explains that older metamorphosed sea floor rocks have been thrust up to form the Keddie Ridge area south of Westwood (west of Lake Almanor), but the majority of the outcrops in the area are relatively younger volcanic rocks including basalt and andesite flows. Lassen Peak is the southern most of the active Cascade Volcanoes and is clearly visible from both Hwy 36 and Hwy 89, the byways that outline Lake Almanor.
Located just a few miles northwest of Lake Almanor, a trip to Lassen Volcanic National Park (The Park) is a must for all Byway travelers. The Kohm Yah-mah-nee Visitor Center (south entrance) and the Loomis Museum (north entrance) are definite stops that showcase the volcanic wonders of the Park. Near the northern entrance you will also see Lassen Crossroads Information Center—giving you a plethora of information on the geology of the area, as well as the historic, ecologic, and recreational information.
Thumping mud pots, boiling pools, steaming ground, and roaring fumaroles are born out of the geologic dance of fire and ice in The Park. Water from rain and snow that falls on the highlands of the park feed the hydrothermal system. According to The Park’s interpretation, “Once deep underground, the water is heated by a body of hot or molten rock beneath Lassen Peak. Rising hot water boils to form boiling pools and mud pots. Super-heated steam reaches the surface through fractures in the earth to form fumaroles such as those found at Bumpass Hell and Sulphur Works.” Other areas of hydrothermal activity include Little Hot Springs Valley, Pilot Pinnacle, Devil’s Kitchen and Terminal Geyser.
All four types of volcanoes found in the entire world are represented in Lassen Volcanic National Park and within the Volcanic Legacy Scenic Byway. Volcanoes found in The Park include shield volcanoes like Prospect Peak, plug dome volcanoes like Lassen Peak, the remnants of a composite volcano called Brokeoff Volcano, and cinder cones, aptly named “Cinder Cone”.
As defined by the United State Geological Survey (USGS), composite volcanoes are “typically steep-sided, symmetrical cones of large dimension built of alternating layers of lava flows, volcanic ash, cinders, blocks, and bombs and may rise as much as 8,000 feet above their bases.” Nearby Mount Shasta is an example of a composite volcano. In contrast, “shield volcanoes are more gently sloping ... and built almost entirely of fluid lava flow. It is a volcano that resembles an inverted warrior's shield as with the Medicine Lake Shield Volcano.
A plug dome is a “steep-sided, rounded mound formed when viscous lava wells up into a crater and is too stiff to flow away. It piles up as a dome-shaped mass, often completely filling the vent from which it emerged.” Black Butte—between the towns Weed and Mt. Shasta--is another example of a plug dome. A cinder cone, the simplest type of volcano, “is a steep-sided volcano formed by the explosive eruption of cinders that form around a vent.”
North of The Park, the byways running through the Hat Creek Valley (on Highways 89 & 44) tell a story of dramatic geologic events. Less than 20,000 years ago the lava of the Hat Creek flow was discharged in large volumes from a series of north-south fissures. This river of lava located near the town of Old Station, crawled northward 16 miles, covering the floor of Hat Creek Valley. While the top crust cooled and hardened, rivers of red-hot lava insulated by newly formed rock above, continued to flow. Eventually, the lava drained away, leaving tube-like caves. The entrance to the Subway Cave, the largest accessible tube in the Hat Creek Flow, was formed by a partial collapse of the cave’s roof many years ago. The Spattercone Nature Trail marks the origin of the flow. While the Subway Cave is found just before the 44/89 junction near Old Station, the Spattercone Trail is 3 miles past it, just across from the Hat Creek Campground.
A few miles further west on Highway 44, The Hat Creek Rim Overlook will show you a large fault scarp where nearly 1 million years ago, active faulting slowly but surely dropped an enormous wedge of the Earth’s Crust 1000 feet below the top of the Hat Creek Rim. Today the fault system is still “alive and cracking.” Explorers can also catch sight of the Hat Creek Valley, Lassen Peak, Burney Mountain, and Mt. Shasta from this overlook.
Traveling further north on the peaceful, meandering byways on Highway 89 bring you through the waterfall region toward the historic town of McCloud. McArthur-Burney Falls State Park, seven miles beyond the Highway 299 junction, has a 128-foot fall that was created from deep within the horizontal layers, or “sills”, of an ancient shield volcano. Just six miles south of McCloud , are the McCloud Waterfalls where glaciers and springs across the eastern slopes of Mt. Shasta flowed downward over Pleistocene lava flows, eventually accumulating in the McCloud River. The river drops about 6,000 feet from its headwaters, over three falls. Between these waterfalls you will also pass the town of Bartle--a beginning and ending point of a geologic loop tour that touches on the Modoc Volcanic Legacy Scenic Byway. A quick detour heading south on Highway 89 and I-5 will bring you to more waterfalls—Hedge Creek Falls--and to Castle Crags State Park whose jagged spires formed some 200 million years ago.
In the heart of The Byway regally stands Mt. Shasta, the second tallest peak of the Cascade Range at 14,162 feet. Peter Skene Ogden, a chief trader with the Hudson's Bay Company, named Mt. Shasta after a Native American who lived in the area on February 14, 1827, according to a United State Geological Survey.
Dr. William Hirt, geology professor at the College of the Siskiyous in Weed, California, describes how Mt. Shasta came to be: “The present Mt. Shasta has been built during the past 250,000 years in a series of four eruptive episodes. The first episode formed the Sargents Ridge cone, whose glaciated core rises above the Old Ski Bowl. Later eruptions added Misery Hill near the mountain’s top and Shastina, the secondary summit. Finally, the last cycle produced the Hotlum dome which forms the present summit. Each episode began with violent eruptions from a central vent that sent hot flows of rock and gas (2000°F) sweeping down the mountain’s flanks.” Today, Hirt explains, “Weed and Mount Shasta City are both built on deposits from these flows that occurred about 9,400 years ago during the episode that built Shastina. As each eruptive episode drew to a close, a plug of pasty lava welled up into the vent, sealing it and building a rounded dome. Black Butte, to the northwest next to I-5, is an example of a dome that formed low on the flank of the Mt. Shasta rather than at one of its major eruptive centers. Its summit peaks mark the top of the dome, which is now largely mantled by a steep apron of loose blocks. It is not a cinder cone, as some believe, but part of Mt. Shasta’s volcanic center.”
A subject for many Native American myths, the Shasta Indians believed that the Great Spirit first created the mountain by pushing down ice and snow through a hole from heaven, then using the mountain to step onto the earth. Mt. Shasta is often visited by spiritual sojourners for its perceived sacred qualities. Its sphere of influence is great from most any view.
At this point, a 6 mile jaunt on Highway 5 to the will bring you on a detour North from Mt. Shasta will bring you by the Black Butte volcano--a plug dome often mistaken for Mt. Shasta on cloudy days—to the historic town of Weed and Highway 97. Highway 97 travels through the Butte Valley-an area dropped down between faults and encircled by volcanoes to form a closed drainage basin. Here the down-faulted valley has subsequently been filled to its present elevation of 4,250 feet by alluvial debris washed into the valley from the surrounding volcanic mountains, by lava flows and by lake deposits.
Traveling on Stateline road (east on Highway 161 and south on Hill Rd) will lead you into the Klamath Basin Wildlife Refuge Complex. The refuges are on the Pacific Flyway, one of four major migratory bird routes in North America and offer ample occasions for great bird watching. According to the U. S. Fish and Wildlife, “Wetlands on the refuges are among the most prolific waterfowl and marsh bird production areas in the Pacific Northwest.”
Nearby, the moody skies of the high desert wilderness reflect the tumultuous geology and history of the Native Americans and early setters at the Lava Beds National Monument. Here, you learn about earth sciences and can look inside the lives of the Klamath and Modoc Tribes, the early homesteading families, the Civilian Conservation Crew, and the Japanese interned at nearby segregation camps during World War II.
The Lava Beds National Monument rests on the northern flank of the Medicine Lake Shield Volcano. Eruptions from nearly 200 surface vents formed a volcano with a low, broad, gently sloping shape. This form built up over time by relatively mild eruptions of fluid lava flowing over large areas. This volcano measures 150 miles around the base, 7900 ft in height, and covers over 700 square miles. Lava Beds Education Coordinator Angela Sutton explains, “It is the largest volcano in volume by far in the Cascade Range.“
Spatter cones, cinder cones, ‘lava beds’, and almost 700 tube caves are types of lava features that resulted from eruptions of the Medicine Lake Shield Volcano over the past 500,000 years. Through a process called subduction, eruptions are ignited by a tectonic plate beneath the Pacific Ocean slowly sliding underneath the continental plate. According to the NPS, “As the tectonic plate dives deep into the earth, this oceanic plate melts into magma, which then rises to the surface as lava several hundred miles inland from the coast. The Medicine Lake volcano is one of many places where these eruptions occurred throughout the Cascade Range of volcanoes, which stretches from northern California into British Columbia. “
Of note, Glass Mountain--named for its exquisite obsidian located about 25 miles south of the Lava Beds National Monument--is a very recent eruption on the eastern flank of the Medicine Lake volcano. Also, Schonchin Butte, a historic fire lookout within the Lava Beds, has panoramic views of the Medicine Lake Volcano, Mount Shasta, Mount McLoughlin, the Clear Lake Hills and the Warner mountains.
Finally at the northern tip of The Byway, Mount Mazama’s successor--Crater Lake delving down to 1943 feet-- took place as the “seventh deepest lake in the world and the deepest in the United States,” according to the National Park Service. About 500,000 years ago, Mount Mazama once commanded 12,000 feet and was considered to be one of the highest mountains of the Cascade Range.
The National Park Service maintains that about 7,700 years ago, “the event that heralded the doom of Mt. Mazama was the opening of a vent somewhere on the north side of the mountain. Lava flows actually traveled up to 25 miles beyond the base of the volcano. As the volcano emptied itself of molten rock, an empty chamber was left underground. The mass of the mountain collapsed in on this void within a matter of days after the eruption. What was left, a 4,000 foot deep caldera and a myriad of other geologic formations.” Over the next several hundred years following the creation of the caldera (meaning “kettle” or “boiler” in Spanish) , the large basin-shaped depression was filled with rain and snow to 1,943 feet, thus creating the clear, blue waters of Crater Lake. Even as the lake began to rise, lava poured into the Caldera. Today, Wizard Island, a small volcanic island appears on the west side of the lake.
From Crater Lake National Park to “the Sleeping Giant,” from the great white Mt. Shasta to the Hat Creek Valley, from Lassen Volcanic National Park to Lake Almanor, we can learn about a life that existed before our own. Wherever you decide to start your journey along the Byway, there is a kingdom of waterfalls, lakes, rivers, wildlife, trees and flowers, outdoor activities, history and culture to bewilder you on your volcano to volcano voyage.
The Volcanic Legacy Scenic Byway can be accessed most of the year, However, snow can cause dangerous conditions and road closures at times. All persons traveling in the wintertime do so at their own risk. Travelers should carry chains and/or a four wheel drive vehicle, have some winter driving experience, and use extreme caution. It is also recommended that you check regional road conditions often.
The road through Lassen Volcanic National Park can be closed from December through to July due to heavy snowfall. Please call the Park directly for current updates.