Rock Star GeoTours

07/31/2023

Saw some beautiful columnar joints at the Columns of the Giants on Hwy 108 (Sonora Pass) in the Sierras. Interesting feature! Had never been there before. Looks like 2 phases of cooling: maybe a lava lake followed by an irregular flow?

07/21/2023

Just one more day until Bodega Head Rocks! Join Rock Star GeoTours from 10am to 1pm at Bodega Head to learn about local geology, rocks, the San Andreas Fault, and the Hole in the Head. Hope to see you there! Learn more and register at

Ever wonder about local geology, the San Andreas Fault, and the Hole in the Head? Learn about rocks, faults, and California’s landscape.

07/07/2023

Two more weeks until Rock Star GeoTours has an outing at Bodega Head on Saturday, July 22! Learn about local Sonoma County geology, coastal erosion, the San Andreas Fault, and human creation of the Hole in the Head! Register at Eventbrite:

Eventbrite brings people together through live experiences. Discover events that match your passions, or create your own with online ticketing tools.

06/28/2023

Bodega Head Rocks! Saturday, July 22nd, from 10am to 1pm, join like-minded geo-nerds at the Bodega Head to learn about movement on the San Andreas Fault, the famous Hole in the Head, and Sonoma County's geologic history. Hosted by Rock Star GeoTours.

05/09/2023

This is just about right!

05/08/2023

Cave pearls in Carlsbad Cavern, New Mexico

Carlsbad Caverns National Park is a United States National Park in the Guadalupe Mountains of southeastern New Mexico. The primary attraction of the park is the show cave, Carlsbad Cavern.

The cave deposit, also called speleothem, any of the crystalline deposits that form in a solution cave after the creation of the cave itself. These deposits are generally composed of calcium carbonate dissolved from the surrounding limestone by groundwater. Carbon dioxide carried in the water is released as the water encounters the cave air; this reduces the water’s capacity to hold calcite in solution and causes the calcite to be deposited. These deposits may accumulate to form stalactites, stalagmites, flowstone, helictites, cave pearls, and many other formations. Deposits formed along ceiling cracks may produce drip curtains or draperies that may then reach the floor to become walls. Speleothems may grow in pools to form the nodular encrustations of cave coral or the natural dams that continually elevate themselves through accretion of calcite. The pure white of the calcium carbonate is often tinted with hues of red, yellow, and gray and may even be translucent. The growth rate of speleothems is highly variable due to seasonal variations in the rate of flow, carbon dioxide content, and other factors. Caves owe most of their beauty and much of their interest to these secondary growths.

05/08/2023

05/05/2023

Is this not amazing?!?! Columnar joints and a mid-ocean ridge make Iceland a spectacular geological playground.

Studlagil Canyon in Iceland 💚 💙
📷

05/01/2023

The Cedars Ecological Preserve is an otherworldly place to study geology, more closely resembling the surface of Mars than Earth. Largely made of serpentinite, there is ongoing active serpentinization happening at this location – on land, in Sonoma County! The serpentine soils are host to a whole community of plants that are endemic to just this piece of property. Enjoy a beautiful grotto with waterfall, various mineral pools, and epic views. The property is BLM land surrounded by private property, so the Cedars is not accessible without a pre-arranged tour.

Join Rock Star GeoTours on June 24th for an 8-hour geotour to and around the Cedars property led by naturalist Roger Raiche. For more information and to sign up, go to:

Discover unique natural beauty at the Cedars Ecological Preserve! Learn about geology, serpentinization, endemic plant ecology and more...

04/26/2023

Isn’t geology just amazing?

📸 Polished Moss Agate cab from Indonesia.
Credit Geology Wonders
Photo: Georgios Chatziparaskevas
NFS - Not For Sale.

04/26/2023

Today is (who knew?) National Richter Scale Day, in honor of Dr. Charles Richter’s birthday.

Apparently, he borrowed the concepts of magnitude and amplitude from astronomy, rather than basing his scale on what people feel during earthquake shaking.

Learn about the history of Earthquakes, and how the Richter Scale measures them, or host an earthquake-themed movie party with friends or family.

04/25/2023

Join fellow geo-nerds on a trek to the Cedars Ecological Preserve! This geotour is a rare opportunity to experience a one-of-a-kind landscape (actually looks more like a Mars-scape)! The Cedars boasts ultramafic geology (serpentinite), unique flora (7 species of plant found nowhere else on Earth), sweeping vistas, a beautiful grotto with waterfall, and the headwaters of Austin Creek.
Guided by noted botanist and conservationist Roger Raiche, we will access this isolated BLM land which is otherwise largely inaccessible.
Reserve your spot now!

Discover unique natural beauty at the Cedars Ecological Preserve! Learn about geology, serpentinization, endemic plant ecology and more...

04/20/2023

Too cool!

Absolutely Gorgeous larger Agatized Dinosaur Bone Rough Slab.

Photo Copyright ©️

04/20/2023

More spectacular petrified wood!

225 million-year-old petrified opal tree trunk located in Arizona 😍

Read more: http://bit.ly/3kjmpLr

04/20/2023

Great tips for beach-loving rock hounds!

Collecting rocks on ocean beaches is one of the easiest and most relaxing ways to rockhound. Here is a guide for what to look for on your next beach trip!

04/19/2023

Bodega Head Rocks! Do you ever wonder about local rocks, the San Andreas Fault, and the Hole in the Head? The landscape you see is largely controlled by the geology under our feet!

Join Stewards of the Coast and Redwoods on Sunday, May 21, 2023 from 10AM to 1PM with Rebecca Perlroth, and discover how the Bodega Head area showcases our region’s fascinating geology, and walk away with a better understanding of the forces (including humans) which have shaped this landscape through time. Learn about geology, rocks, faults, and California’s amazing and complex geologic history.

This event includes a slow-paced relatively easy hike around the 1.7 mile loop trail at Bodega Head, with some off-trail walking. Some of the trails include varied terrain and uneven surfaces.

Visit Stewards of the Coast and Redwoods for more info and to register.

04/18/2023

Through the Stewards of the Coast and Redwoods, I’m doing a geology walk at Bodega Head on May 21st, from 10am-1pm. For more info, visit: https://stewardscr.org/events/geology-of-bodega-head-2023/. Space is limited!

Geology of Bodega Head 2023

04/11/2023

Check out our list of the top 5 museums for geology lovers, where you can see rare rock formations, interactive exhibits, and more. Get ready to be amazed by the beauty and complexity of the Earth's geologic past.

04/11/2023

Things every good geo-nerd should carry!

Here are the top rockhounding tools that are available today. We've narrowed the list down to the best tools you should add to your rockhounding tool kit.

04/11/2023

Join us on a visual tour of the most stunning rock formations in the world. From the breathtaking Wave in Arizona to the majestic Uluru in Australia, these natural wonders will take your breath away.

04/06/2023

Consider joining one of my favorite colleagues, Shawn Brumbaugh, of the Biology Department at SRJC, at his presentation: "Tidepools, Redwoods & Acorn Woodpeckers. A Natural History Homage to Sonoma County", presented on April 21st at 6:30pm at the SRJC campus in Santa Rosa. should be a great talk!

04/05/2023

Benitoite, natrolite and crossite under short wave UV light.
California, USA
https://www.rockseeker.com/10-stunning-rare-gemstones/?utm_campaign=meetedgar&utm_medium=social&utm_source=meetedgar.com

04/05/2023

Ever wonder if there's a fossil hidden inside a rock? Learn expert insights from Mamlambo Fossils as he guides you through the fascinating process of identifying fossil-bearing rocks!

03/13/2023

Join RockStarGeoTours on April 8, 2023 on a geology focused trip to the Sonoma Coast. We will cover coastal geology, the San Andreas Fault, identification of local rocks, formation of the Coast Ranges and more! Save the date and register today! I CAN'T WAIT to see you all there! Get more information and register at rockstargeotours.com

03/13/2023

This is the first rock I remember collecting, back in the 4th grade. We were doing a poetry assignment at school, and we went to the creek behind campus, where I found this! I was on the SF peninsula, near Woodside, CA. I couldn't believe I was so lucky... No idea what species this is, but I have always considered this one of my prize specimens.