Rediscovering Rocks: A Geologist’s Journey Back to the Field

Normal fault mimics regional structure

King Canyon Hike

John Wakefield at the King Canyon Trailhead

John Wakefield spent 25 years traveling the world, to Botswana, Portugal, Spain, Zambia, Saudi Arabia, and Brazil as an exploration geologist and visiting professor. During this period, geology was an all-consuming passion as well as a job. In February 2024,  after nearly 40 years without hitting a rock in anger, John decided to dust off his trusty Estwing and see if his rock-hammering skills were still operational. 

And guess what? He wasn’t alone on this adventure! He had the company of the one and only Mike “West Virginia” Breiding, a hiking guru now based in Tucson who knows the local flora and fauna like the back of his hand. (Marvel at Mike’s hiking achievements by following this website).

Together, they embarked on the King Canyon hike to Gould Mine, drawn by its awesome rock exposures and ancient Native American petroglyphs.

Location map of King Canyon

As an Amazon Associate, I earn from qualifying purchases

Tucson Mountain Park served as their playground, boasting a colossal volcanic caldera that formed a whopping 70 million years ago, back when dinosaurs still roamed the land.

Now, let’s get into the nitty-gritty. Picture this: we found a dislocation in the Amole arkose, a rock formation dating back around 80 million years, caused by what we call a “normal” fault. If you’re scratching your head about what that means, don’t worry – take a look at the image below to see the difference between a normal and a reverse fault.

Two types of geological faults are normal and reverse

Here’s the interesting part – structural geologists use mesoscopic (outcrop-scale) structures to help figure out regional or large-scale geological structures.

Normal fault mimics regional structure
Normal fault in Amole arkose mimics regional faulting

Notice how the extensional stresses that caused this minor fault are the same type of forces that created the crustal extension that occurred about 25 million years ago.

Just imagine the Earth’s crust playing a game of tug-of-war, with one side pulling away from the other. That’s basically what’s happening here. 

Outcrop showing normal fault
Regional cross section showing normal faults in the Tucson area
Regional structures mimic structures in outcrops

(Note to geologists: Spencer et al. (2019) believe this extension was associated with “core complex” uplift which occurred in Oligocene to Miocene times – follow this link for details.)

Want to look like a real geologist?

Purchase a genuine Estwing rock pick – 22 oz geology hammer with pointed tip & shock reduction grip.

ESTWING Rock Pick - 22 oz Geology Hammer with Pointed Tip & Shock Reduction Grip - E3-22P

Buy this classic Estwing from Amazon and DON’T FORGET TO WEAR EYE PROTECTION!


Finally, we fast-forwarded from 75 million years to a few thousand years ago as we examined cryptic petroglyphs – Native American art chipped through the desert varnish to intrigue and puzzle modern-day hikers.

Petroglyphs in King Canyon Tucson
Have fun trying to figure out what was going through the minds of these ancient rock artists

Explore the fascinating subject of Rock Art Symbolism with the aid of this book from Amazon

Protect your eyes with safety goggles!

Dewalt DPG82-11C Concealer Clear Anti-Fog Dual Mold Safety Goggle, Clear Lens, 1 Pair

Buy these excellent goggles on Amazon – don’t take a chance with your eyesight!

Follow this link to learn about the Tucson Mountain Park Volcanic Caldera!

After nearly 40 years without hitting a rock in anger, John Wakefield decided to dust off his trusty Estwing and see if his rock-hammering skills were still operational. 


I was an exploration geologist and University Professor working in Botswana, Zambia, Brazil, Saudi Arabia, the Netherlands, Portugal, and other countries before opening Artistry in Glass in 1986. In my more than 35 years of experience, I have brought my technical abilities as a scientist to the trade of glasswork. During this time I have become an industry expert in glass and glass-related skills. Watch out for special insider tips developed from my detailed knowledge of the glass business.

Recent Posts