PlanetGeo: The Geology Podcast

Latest Episodes:

Asteroids and Extinctions: Excerpt from Interview with Dr. Ian Miller (Geoshort) May 20, 2021

Show notes

In this GeoShort, Dr. Ian Miller (Director of Earth and Space Sciences, Associate Curator of Paleobotany for the Denver Museum of Nature and Science) compares the end Cretaceous event that killed the Dinosaurs to other mass extinction events.
Jesse and Ian also have a brief discussion about massive lava eruptions that can cause mass extinctions such as the Deccan Traps.
Ian also provides an excellent explanation on how fossils form!

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Glacier National Park May 13, 2021

Show notes

Learn all the basics of geology in our new conversational textbook - campGEO!
Available here: geo.campcourses.com
Today we are talking about the geology of Glacier National Park! We cover three major things:

1- The Colors: The rocks in Glacier have stunning colors and you can see them almost anywhere in the park. The main colors are various shades of red, green, brown, and gray.

First off, focus on the reds: These rocks have a mineral called hematite (Fe2O3). Hematite forms when iron bearing minerals react with O2 to produce the iron oxide. This happens either on land or in shallow enough water so the minerals have access to free O2 from the atmosphere. In Glacier, we know this definitely happened in shallow water. How do we know this? These red rocks contain sedimentary structures such as ripple marks that only form in shallow water….. If rocks have as little as 3% hematite, it can stain the rocks bright red.
Green: These rocks formed in deeper water. In chemistry, we call this a reducing environment (as opposed to an oxidizing environment for the red rocks). Because there is less O2 present in the deeper water, the iron doesn’t combine with oxygen, and instead binds with silica to produce dark minerals like hornblende, biotite, and others. But, these minerals aren’t as stable as hematite and turn into a green mineral called chlorite with burial.

So why do the red and green rocks alternate as they are stacked up on top of each other?

2- The Mountains:

Most of the rocks we see in the park were sedimentary. A shallow sea was depositing sedimentary rocks for a very long time (over 18,000 feet). The sea was actually a result of early continental rifting and higher sea level.
Long after the deposition of the rocks we see, tectonics began to influence the area. Sedimentary rocks are laid down flat. The rocks in Glacier are not flat - they are folded and tilted. This tectonic event is the same event that formed the Rockies extending from Canada to Northern Mexico. An oceanic plate was subducting beneath the North American plate.

3- Glaciers:

Beginning 2 my ago and ending 20,000 yrs ago, glaciers grew and filled the valleys with immense systems of moving ice. These powerful, slow, relentless glaciers carved Glacier NP into the rugged beauty we see today. Although there are active glaciers still today Glacier NP is named for the features that formed during the Ice Age rather than being named after the remnants barely hanging on today. Glacier NP is a textbook for features like cirques, aretes, U-shaped valleys,

Lakes fill in these U-shaped valleys. On the map view they look like fingers! Very similar to Finger Lakes area in western NY State and formed similarly, glacially scoured valleys that now have lakes in them.

Another interesting difference between Glacier and other parts of the Rockies is that there are no foothills to the East (think Denver, Calgary, etc). You go from Prairies to Mountains very quickly. This is because glaciers did a TON of erosion and all the sediments were deposited in the valleys to the East. So, the foothills are there, just buried by pieces of the mountains

Glacier Questions From Our Live Event (GeoShort) May 06, 2021

Show notes

We recorded a live podcast episode with Mappy Hour!
We recorded a live episode on the Geoscience a really special place, Glacier National Park and Waterton National Park in Northwestern Montana and Southern Alberta. The geoscience of these parks is truly special and there are great stories everywhere.
A few of the things we mentioned in these questions are the book Geology along the Going-To-The-Sun Road and the Roadside Geology book series. Check them out for some great info!

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Discovering Ancient SuperQuakes: Why Large Earthquakes Occur and Where Apr 29, 2021

Show notes

Exciting news! This Tuesday, May 4th, we will be doing a live podcast recording with Mappy Hour. Register below!
PlanetGeo Mappy Hour Live Recording - Glacier National Park

Today we talk Earthquakes!
The list of EQ dating back to antiquity is shocking. The amplitude and deaths caused are estimated, but a glimpse of this list is very sobering. Below is a list of some of the important and more recent.

Medieval Europe (italy, spain, portugal) were all very aware of the risks of Earthquakes and were starting to apply new engineering specifically for earthquake mitigation (anchor plates in buildings, exaggerated buttresses).
1700: The Cascadia subduction zone. Research by Brain Atwater has revealed when this EQ occurred. Estimated to be 8.7 - 9.2 moment magnitude. Atwater has discovered ghost forests of red cedars that were killed by being lowered and submerged in salt water as a result of a massive EQ. The tree rings date back to 1699 - the last growing season before the EQ. Records in Japan confirm a tsunami that caught them offguard.
December, 1811 to February 1812: 3 large EQ in New Madrid, MO 8.1,7.8 8.0. Caused by old stress from a failed rift zone.
1906: San Francisco EQ 7.9
1964: The Great Alaskan EQ. 9.2 the shaking lasted 4 min and 38 seconds. The Richter scale put these two as the same strength.
1976: China. 7.6 EQ that unlike the year before, no foreshocks or warnings. Estimated up to 750,000 people died.
2004: Sumatra 9.1 227,000 people died
2009: L’Aquila, italy, 5.8, 309 people died; Italian seismologist went on trial for incorrectly reassuring the population that no earthquake would occur. Earthquake was predicted by one researcher a month before, he was called alarmist. Then the earthquake occurred and 7 people (6 scientists and one official) were convicted of giving false or misleading statements that downplayed the risks. This result was criticized by most major scientific organizations and outlets. These verdicts were later overturned by the Italian Supreme Court 2014
2011: Japan 9.0 Almost 21,000 people died

It’s also appropriate to talk about the exponential scale. The richter scale is outdated and really measures the amplitude and distance the waves travelled. It’s not accurate in discerning major EQ. The moment magnitude scale measures the amount of movement along a fault and the force required to make that movement. It also measures all of the seismic waves produced by an EQ.

The scales vary logarithmically. In terms of the amount of ground shaking, a difference of 1 varies by an exponent of 10. But in terms of energy released, it varies by powers of 30 (We round to 30. It’s actually 31.6. That means that for each increase in .2, the energy released is doubled)
Why do Earthquakes occur?

1 - Think back to the plate tectonics episode. The movement of tectonic plates causes stress along the plate boundaries.

Use N. America as a starting point (more on the west coast, few on the east coast) but then we compare them to other countries like Germany and the UK (which have very few) Italy (lots of earthquakes with >10,000 killed) and western Pacific (same).

2.5 Billon Tyrannosaurus rex (GeoShort) Apr 22, 2021

Show notes

This is an Earth Day special! Today we are talking about this really cool study that came out last week in the scientific journal Science (one of the top journals in all of ‘science’).

It is by Charles Marshall and others from Berkeley, and the title is “Absolute abundance and preservation rate of Tyrannosaurus rex”
https://science.sciencemag.org/content/372/6539/284

The authors also wrote this very cool Conversation (name of the publication) article where scientists and journalists co-write a summary of research.
https://theconversation.com/how-many-tyrannosaurus-rex-walked-the-earth-159041

Well the title pretty well describes what this paper is about, but let’s go through the arguments here, and hopefully we will get a chance to talk to one of the authors of this study at some point in the future!

So, here’s what ‘we’ as the field of science knew before this paper:

T. rex mated ~15 years old
Estimates of how long each dinosaur lived
T. rex walked the Earth for 1.2 to 3.6 million years
Rough estimate of metabolic rate, somewhere between mammals and komodo dragon

Armed with this information, Marshall et all performed this cool calculation. First they figured that each generation of T. rex took ~19 years (average time between consecutive lineages, humans are between 22 and 33)

They then needed population density to figure out how many dinosaurs there were at any one time. So they applied this relationship between body mass (size) and population density for modern animals (Damuth’s law). Square mile of grassland supports more rabbits than elephants…Damuth’s law is also dependent on metabolic rate, so apply that data.

They get an average of 1 T. rex every 42.4 square miles, or 109.9 square km. This is two individuals in Washington DC! Ottawa county is 583 square miles, ~13-14 T. rex.

This calculation can then go one stage further and estimates that ~20,000 individual T. rex were alive at any one time, and 2.5 BILLION T. rex ever existed on Earth! That’s amazing!

So, there may be some debate about the actual numbers involved here (and these have a massive uncertainty, between 130 million T rex and 42 billion, using conservative uncertainty stats), but for us it teaches us two important points:

There is a method to uncertainty calculation that is a good lesson here: These calculations are all pretty uncertain, how do we know how reliable these final numbers are?
Fossils, especially land fossils, are a very very rare thing!

Ancient Nukes: 1.9 Billion-Year-Old Nuclear Reactors Apr 15, 2021

Show notes

Did you know that nuclear fission reactions are natural? Uranium fission drives many types of nuclear power plants as well as nuclear weapons. However, these types of reactions occurred on Earth naturally, just billions of years ago. Today, we discuss the Oklo natural fission reactors in Gabon, Africa.
These natural reactors are not only amazingly cool, but they have a really interesting discovery story and they can teach us a lot about the overlap between nuclear physics and geoscience, how uranium deposits form, and what Earth's ancient atmosphere looked like!
These are important for several reasons:

Geology and nuclear physics have a very intimate relationship.
1. Basically all radiometric dating we use on Earth was developed on the back of research on Uranium nuclear physics and research into nuclear weapons/reactors.
Geoscience and national security are intimately related:
1. Nuclear forensics, or using isotope analyses to look for people enriching uranium, use the same techniques and instruments as geochronology
2. Many PhD geoscientists go to work in national security labs/jobs
These natural nuclear reactors help us explain Earth’s history and where Uranium deposits occur.

Another cool feature of these ancient nuclear reactors is that they may have looked much like geysers in Yellowstone National Park! They were moderated by natural groundwater, and they cycled on and off in ~30 minute cycles.
All told, these natural nuclear reactors are one of the single coolest geoscience factoid we know of!

Grand Canyon Hiking Recommendations (GeoShort) Apr 08, 2021

Show notes

Learn all the basics of geology in our new conversational textbook - campGEO!
Available here: geo.campcourses.com
Are you planning a trip to the Grand Canyon soon? Are you interested in seeing some cool geoscience features? Join us today as we discuss a few great hikes to check out while visiting the Grand Canyon National Park in Arizona, USA.
We discuss hiking trails such as the South Kaibab Trail down to the aptly-named Ooh Ahh Point (so beautiful!), and end up at Skeleton Point for a full view of the Canyon in all its glory! Alternatively, you could take the Bright Angel trail, a somewhat nicer hike because of all the restrooms and water stations every 1.5 miles, stop at the amazingly lush Indian Garden, and eventually make your way out to the Plateau Point for a dramatic view directly down to the Colorado River.
The South Rim of the Grand Canyon has an amazing amount of views and hiking that are easily accessible to everyone, even if you don't want to hike very far. For instance, you could start by visiting the small cairns that contain actual samples of the 1.7 billion-year-old Vishnu Schist, or by walking the Trail of Time, where for every large step you take down into the Canyon is equal to going back in time One Million Years in the rock record!
As always, don't feed the wildlife, and downhill hikers always yields to uphill hikers , and everyone yields to mule trains!
If you want to hear an overview of the geology of the Grand Canyon, check out our previous episode covering the full history with detailed descriptions of the major geoscience features of the park. The Grand Canyon has over 1.9 billion years of geology on display, and it is all very visible in a stunning landscape!

The New Climate War: Dr. Michael Mann, Distinguished Professor and Author Apr 01, 2021

Show notes

There is a new climate war afoot. And, there is a book about it! Professor Michael Mann, Distinguished Professor at The Pennsylvania State University, has a long history of studying and discussion climate change. His new book, titled The New Climate War, is out now!
In this episode we interview Mike about his journey in academia, what the new climate war is all about, and what he sees as the best path towards solutions. We discuss how last climate war has ended, what we all can do to fix the problem, and how Dr. Mann sees the future working out.
Send us your questions, thoughts, or suggestions!
Dr. Michael E. Mann received his undergraduate degrees in Physics and Applied Math from the University of California at Berkeley, an M.S. degree in Physics from Yale University, and a Ph.D. in Geology & Geophysics from Yale University.

Dr. Mann was a Lead Author on the Observed Climate Variability and Change chapter of the Intergovernmental Panel on Climate Change (IPCC) Third Scientific Assessment Report in 2001 and was organizing committee chair for the National Academy of Sciences Frontiers of Science in 2003. He has received a number of honors and awards including NOAA's outstanding publication award in 2002 and selection by Scientific American as one of the fifty leading visionaries in science and technology in 2002. He contributed, with other IPCC authors, to the award of the 2007 Nobel Peace Prize. He was awarded the Hans Oeschger Medal of the European Geosciences Union in 2012 and was awarded the National Conservation Achievement Award for science by the National Wildlife Federation in 2013. He made Bloomberg News' list of fifty most influential people in 2013. In 2014, he was named Highly Cited Researcher by the Institute for Scientific Information (ISI) and received the Friend of the Planet Award from the National Center for Science Education. He received the Stephen H. Schneider Award for Outstanding Climate Science Communication from Climate One in 2017, the Award for Public Engagement with Science from the American Association for the Advancement of Science in 2018 and the Climate Communication Prize from the American Geophysical Union in 2018. In 2019 he received the Tyler Prize for Environmental Achievement and in 2020 he received the World Sustainability Award of the MDPI Sustainability Foundation. He was elected to the U.S. National Academy of Sciences in 2020. He is a Fellow of the American Geophysical Union, the American Meteorological Society, the Geological Society of America, the American Association for the Advancement of Science, and the Committee for Skeptical Inquiry. He is also a co-founder of the award-winning science website RealClimate.org.

The Feeling of Discovery with Prof. Michael Mann (GeoShort) Mar 25, 2021

Show notes

Welcome to the preview to our full interview with Professor Michael Mann, prestigious climate scientist and author of the new book, The New Climate War.
Professor Mann is a Distinguished Professor at Penn State University, a member of the National Academy of Sciences, and has won many science and science communication awards.
In this GeoShort we discuss the feeling of discovery that Dr. Mann felt when publishing the 1999 scientific article that documented the "hockey stick" graph of CO2 increase in the atmosphere. Below is a short description of Dr. Mann's award-winning career, and join us next week for the full interview with Dr. Mann covering his new book, The New Climate War!
Dr. Michael E. Mann received his undergraduate degrees in Physics and Applied Math from the University of California at Berkeley, an M.S. degree in Physics from Yale University, and a Ph.D. in Geology & Geophysics from Yale University.

The Grand Canyon National Park Mar 18, 2021

Show notes

Learn all the basics of geology in our new conversational textbook - campGEO!
Available here: geo.campcourses.com
“Crying: acceptable at funerals and the Grand Canyon” - Ron Swanson
Today, we talk about the Grand Canyon. The scenery and geology combine to create one of the Natural Wonders of the World. If you are planning a trip, or would like to learn more about this spectacular location, listen to this episode!
It’s hard to show the principles of stratigraphy better than what’s on display in the Grand Canyon. Each layer gives clues to the environment of deposition and what the Earth was like at the time the sediment was laid down. It’s one of the best example of the geological Laws of Superposition and Original Horizontality on the planet. Other relative dating principles, that are also amazing textbook examples, include the principles of lateral continuity and cross cutting relations.
In this episode you will learn about the three main groups of rock formations on display in the Canyon. Really the only way to talk about them is from oldest to youngest - start at the beginning and work to last page in the book. The three formations are:

1- The Metamorphic Basement Rocks (up to 1.7 BILLION years old!)

2- The Precambrian Grand Canyon Supergroup - all sedimentary rocks with a billion years of missing time.

3- Paleozoic Strata - a continuous record of Earth for ~300 million years.

The bottom line is that the rocks are old, and the canyon is young. We end this podcast with a discussion of the very young volcanic rocks around the Grand Canyon like Sunset Crater, and we also discuss some scientific ideas about how the Canyon formed, a process that started about five million years ago.

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