NSS Convention ~ July 25-30, 2021

Lake Shasta Caverns

Quick Read:

Lake Shasta Caverns were part of life for the Wintu Indians, who lived in the area. In the 1870s, a fish hatchery and small town were built on the McCloud River and the cave was named Baird Cave. A hatchery employee, J.A. Richardson, officially discovered the caverns in 1878. Since 1964, they have been opened as a natural attraction to the public.

This cave will be featured on the mid-week geology tour led by Joel Despain. Click here for complete details.

Lake Shasta Caverns

Lake Shasta Caverns is a National National Landmark and the only limestone show cave in Northern California. When you have a chance during the 2021 NSS Convention, this is a worthy destination to experience. The cave is located in the Permian McCloud Limestone of Shasta and Siskiyou counties and lies about 54 miles south of Weed along I-5.

Lake Shasta Caverns. Photo by Dave Bunnell, Under Earth Graphics.

Lake Shasta Caverns. Photo by Dave Bunnell, Under Earth Graphics.

The cave's extensive speleothems include large numbers of helictites, shields, great spar crystals, a wide variety of stalagmites, and some of the longest and largest curtains in California. Tours run 45 minutes to an hour, but the entire experience is closer to a half day in length. To reach the cave, one must cross Lake Shasta by boat and also take a bus two miles from the lake shore up nearly 1000 feet to the cave entrance. The scenic boat trip and bus ride are included along with cave tour tickets, and both the boats and buses are designed to give people great visibility and views. Shasta Caverns is a vertical cave with many pits and many stairs on the tour.

Tours are a point of pride among the cavern's staff and you can expect to have an informative and fun trip to the cave. Tours feature discussions on the history of the cave, its geology, and on-going research.

History & Discovery

The history of the cave reaches back to the Wintu Native Americans who visited many caves in the region. Europeans became aware of the cave in the late 1800s. During the first half of the 20th Century, many daring visitors descended down ropes and ladders into the caverns. Commercialization began in 1963 with the start of tunnel construction.

Geological Formation

The McCloud Limestone is highly fossiliferous, contains many chert beds and is heavily intruded by Jurassic diorite. Shasta Caverns is believed to be a hypogene in origin. That means that is not a fluvial cave made by a stream, but rather that it formed due to rising water that may have been hot or had unusual chemistry such as sulfuric acid. Likely this was in association with volcanism at Mount Shasta in a process cave geologists call volcanogenic karstification. This kind of cave development is recognized in multiple locations around the world including in Mexico, Italy, and Bulgaria.

The cave has formed on a mapped high-angle thrust fault with an adjacent anticline. This manifests inside in a series of minor-offset faults along which many of the cave passages have formed. Much of the cave is narrow, deep rifts with many sudden passage terminations and dead ends. The cavern is quite old. Work by Dr. Jessica Oester at Vanderbilt showed that one stalagmite was more than 450,000 years old.

Shasta Caverns entrance tunnel. Photo: Visit Redding.

Shasta Caverns entrance tunnell. Photo: Visit Redding.

Public Tours

The tour starts at the lower artificial entrance tunnel. Visitors will notice the many natural voids that the tunnel intersects. There was a lot of dissolution in the limestone away from the main passages. This tunnel intersects the Discovery Room and adjacent passages. This cave was unknown before the tunnel intersected the passage. It was a huge surprise in 1964 when the cave was being commercialized and the tunnel was made. This area is heavily decorated and culminates in the Dome Room. A close look will reveal cubic calcite crystals, spathites and shields. Use a bright light to see the big helictites up on the wall and across the Dome Room. Upon completion of this level, your tour will return to the tunnel and up a long set of stairs to the main cave itself. Along the way are some dry pools with great examples of calcite nailhead spar.

The trail enters the main cave in the very scenic Crystal Room. Be sure to look up to view the high ceiling and many nice helictites. More stairs take one up to the Basement. This room lacks stal, but notice the sulfuric acid karren on the right. On the left, behind a pile of rocks is a pit that leads downward 40 feet into the Spider Complex. This is an extensive section of the cave with interconnected pits and narrow passages.

More stairs lead one up to the Signature Room - where the first to document the cave recorded their names. This room is nearly 100 feet across on the long axis. Notice the pool notches in the walls just below the signatures. There are more connections to the Spider Complex in this room. From here the trail continues upward again with many more stairs to finally reach the grand Cathedral Room.

The Cathedral Room is nearly 100 feet tall and about 100 feet across. On the west wall a large balcony gives way to dozens of very large curtains. There is a lot to see in this room. A bright light is nice to spot all the cool stuff way up on the walls.

Higher up still is the natural entrance and associated passages. Ask your tour guide to point out the holes in the ceiling that connect to this final, highest upper level.

From here your tour will depart the cave out the upper entrance tunnel. But the hike back down is very scenic with great views and lots of fossils and pockets full of speleothems in the limestone. We also recommend the gift shop back across the lake. They have a nice set of unique caving t-shirts.

Shasta Caverns. Photo by Dave Bunnell, Under Earth Graphics.

Today's Weather: Mount Shasta, CA

  • Updated: Saturday, June 12 at 7:17 am
  • Reporting Station: Mount Shasta (KMHS)
  • Elevation: 3,540 ft.
  • GPS: 41.31494;-122.31702
  • Data provided by: National Weather Service
48° F
Mostly Sunny

Regional Map Forecast Wind: none
Humidity: 77%
Dewpoint: 41°F
Barometer: 30.06 in.
Visibility: 10.0 miles

Today: Mostly sunny. High near 78, with temperatures falling to around 76 in the afternoon. South southeast wind 6 to 18 mph, with gusts as high as 28 mph.
Tonight: Partly cloudy, with a low around 56. South southeast wind 2 to 12 mph.