In this episode, we sit down with Dr. Mike Ackerson (Smithsonian) for the kick-off of a deep-dive series on granites and granitoids. This one goes into the weeds: the 250-year history of how arguing about granite shaped nearly every major idea in the geosciences.

We trace the great controversies from the 1700s to today:

🌊 Neptunism vs. Plutonism — Did granite precipitate out of a global ocean, or crystallize from molten rock? How James Hutton's fingers of granite at Glen Tilt helped kill the Neptunist worldview.

⏳ Uniformitarianism & deep time — How Charles Lyell's expansion of geologic time gave his friend Charles Darwin the temporal runway for natural selection. (Yes, the founder of biology was basically a geologist.)

🧪 Magmatists vs. Transformists ("granitizers") — The 20th-century brawl over whether granites are intruded magmas or rocks transformed in place by fluids — and how Bowen, Tuttle, and experimental petrology tipped the scales.

🪨 The Room Problem — Walk across the Sierra Nevada and you cross miles of granite. How do you make space in the crust for that much rock? The 150-year-old puzzle that's still not fully resolved.

Plus: the legendary Norman Bowen "horse equilibria" letter, why H.H. Reid said "he who has seen the most rocks wins," and where the most exciting frontiers in granite petrology lie today — low-temperature magma storage, fluids in the crust, and links to geothermal energy and critical mineral ore deposits.

This is Part 1 of a series — future episodes will tackle the timescales of granite emplacement, geochronology, and a return to the Room Problem.

Want the intro-level foundation first? Download the CampGeo mobile app (first link below) for our textbook-style content on igneous rocks, including a full episode on Bowen's Reaction Series — what is granite, what is basalt, and all the basics.

#geology #granite #petrology #geoscience #earthscience #PlanetGeo #magma #JamesHutton #Darwin #science

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On the app you can get tons of free content, exclusive images, and access to our Geology of National Parks series.
You can also learn the basics of geology at the college level in our FREE CampGeo content series - get learning now!

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In this episode, we sat down with Keith Rapp, senior hydrogeologist, longtime volunteer with ASBOG (the Association of State Boards of Geology), and immediate past president of the organization. We dug into the professional geologist licensure process — what the FG (Fundamentals of Geology) and PG (Practice of Geology) exams actually test, how questions get written and vetted by panels of subject matter experts, why some states require licensure and others don't, and why Keith argues that licensure is fundamentally about protecting public health and safety.

Keith walked us through his path from growing up in Duluth with a geomicrobiologist uncle, to a master's in hydrogeology at Baylor, to a career cleaning up contaminated sites using microbes — what he calls hydrogeomicrobiochemistry. We talked about his current work on PFAS bioremediation, the idea of "pushing evolution" by engineering biofilm environments where microbes can adapt to degrade forever chemicals, and the role of zeolites as remediation media.

We also got into the practical stuff students and early-career geologists actually want to know: how to study for the FG exam, why test scores point you toward weak domains, what reciprocity between states looks like, the difference between an ASBOG license and an AIPG Certified Professional Geologist (CPG) designation, and why writing skills still matter in a hiring pile. We closed with a conversation about AI in geoscience — where it helps, where it gets you in trouble when your name is on a signed report, and how the profession should think about it going forward.

If you're a student preparing for the FG, a working geologist thinking about getting licensed in another state, or just curious about how a professional credentialing system gets built and maintained, this one is for you. The ASBOG annual meeting is in Hershey, PA this October — open to anyone interested in the profession.

Download the CampGeo app now at this link.

On the app you can get tons of free content, exclusive images, and access to our Geology of National Parks series.
You can also learn the basics of geology at the college level in our FREE CampGeo content series - get learning now!

Like, Subscribe, and leave us a Rating!

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Email: planetgeocast@gmail.com
Website: https://planetgeocast.com/

What distinguishes supervolcanoes from regular or non-super volcanoes? How many supervolcanoes are on Earth today? What are the precursors to supervolcano eruptions? In today's deep dive, Dr. Rachel Phillips, from GeoGirl, and I we got to talk to supervolcano researcher, Dr. Shan de Silva, to answer all your supervolcano questions (and more)!

Download the CampGeo app now at this link.

On the app you can get tons of free content, exclusive images, and access to our Geology of National Parks series.
You can also learn the basics of geology at the college level in our FREE CampGeo content series - get learning now!

Like, Subscribe, and leave us a Rating!

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Instagram: @planetgeocast
Twitter: @planetgeocast
Facebook: @planetgeocast
Support us: https://planetgeocast.com/support-us
Email: planetgeocast@gmail.com
Website: https://planetgeocast.com/