Category Archives: Uncategorized

Episode 12 – “You want to filter out the ducks” Tides

Tides pull and deform the surface of the ocean and the surface of the Earth. This week we’ll take a quick tour of tidal forces, address some show feedback, and then talk about a revision on a classic physics problem.

Tides

  • Tides are a result of gravitational interaction of the Sun-Earth-Moon system, but are of course a factor on many other planets as well.
  • Gravity is the key to remember and that it varies linearly with mass, but with the inverse square of displacement.

Ocean Tides

  • The most familiar example is ocean tides. These are important for commerce, safety, and for sedimentary processes.
  • Sedimentary layers called tidal rythmites
  • Cool tide visualization from Calculated Images
  • General cycle is a flood tide raises water levels until high tide. Then an ebb tide takes water back out until low tide is reached. When the tidal stream stops and reverses it is a slack tide.
  • Generally occur with 24-hour or 12-hour period, can have a complex shape.
  • Another kind of clock, a tide clock, has been made to show this.
  • Spring tide has nothing to do with the season.
  • When planets are aligned, it’s called a syzygy. Word of the week.
  • A really nice mathematical introduction can be found here.

Tide Gauges

  • A pole with markings that we read off of
  • A float and weight on a pulley attached to a paper chart recorder
  • Pressure gauges or bubbler pressure measurement
  • Acoustic gauges or radar gauges (time of flight)
  • There is a whole mess of datums and standards that go into this, but let’s not go there today!
  • And rocks of course!!

Solid Earth Tide

  • The same forceings as ocean tides, but we are actually moving the surface of the planet here. Very important for GPS and scientific measurements. Large particle accelerators actually compensate for their deformation.
  • The largest displacements are around 55 cm!
  • Needed to explain the Earth’s nutation
  • Lunar Tidal Heating

Tidal Locking

  • We can only see one side of the moon because it is tidally locked. It rotates at the same rate that it orbits the Earth.
  • Checkout the Minute Earth video on tidal locking!

Feedback/Followup

Fun Paper Friday

We’ve all had to solve the classic physics problem of what would happen if you dug a tunnel through the center of the Earth and jumped in. The classic answer has been that you’ll move like a damped oscillator and that your fall will take about 42 minutes. By improving some of the assumptions that are used, that answer has been improved.

Klotz, A. R. (2015). The gravity tunnel in a non-uniform Earth. American Journal of Physics, 83(3), 231–237. doi:10.1119/1.4898780

Contact us:

Showwww.dontpanicgeocast.com@dontpanicgeo – show@dontpanicgeocast.com

John Leemanwww.johnrleeman.com@geo_leeman

Shannon Dulin@ShannonDulin


New episode!

Leave a Comment

Filed under Uncategorized

Episode 9 – “There’s an app for that”

This week we thought it would be a good idea to recap some of the apps that we use on a daily basis to get our work done. We want to explicitly state that we are fully unsponsored and that these are just our opinions, not official recommendations or endorsements We chose iPhone/iPad apps since that’s what we and many of our colleagues use. A lot of these are transferrable to the Android or other platforms. Don’t tune out or you’ll miss some tips that will help you, no matter what the platform you use is.

John’s App Picks

Shannon’s App Picks

Misc Links

Fun Paper Friday

This week we read about building sandcastles! Turns out that a lot of the worlds energy (about 10%) goes to handling granular materials and that we can learn a lot by examining simple sand.

Pakpour, M., Habibi, M., Møller, P., & Bonn, D. (2012). How to construct the perfect sandcastle. Scientific Reports, 2. doi:10.1038/srep00549

Contact us:

Showwww.dontpanicgeocast.com@dontpanicgeo – show@dontpanicgeocast.com

John Leemanwww.johnrleeman.com@geo_leeman

Shannon Dulin@ShannonDulin


New episode!

Leave a Comment

Filed under Uncategorized

Episode 8 – “Canal Side Geologist” Making Maps

What is a geologic map?

  • Conveys many sorts of geologic information
  • The whole basis of field geology
  • Can be a surface,bedrock, subsurface, resource, soil, etc. map

Making the Map

  • Start off with your field gear…like we talked about in episode 2. We said episode 1 in the show, but that was wrong!
  • Have a base map (Geomorphologic map—we call these topos)…you need to know where you are at
  • You can use an iPad/GPS with pre-loaded topo maps, or you just have your paper basemap.
  • John likes the Garmin 62S GPS unit
  • You don’t want to become too reliant technology in the field because it could be a life or death situation
  • You need to have done your research before you go

History of geologic maps

  • Book: The map that changed the world, by Simon Winchester
  • 1793 [William Smith](http://en.wikipedia.org/wiki/William_Smith_(geologist), who was a surveyor working for canal builders, was paying attention to all the layers of rock that he was digging through
  • He noticed that he could trace the different layers of rock that were stacked on each other
  • He also noticed the different fossils inside them meant that the rocks were the same age and could be traced all over
  • Would study coal seams, which could be easily traced and spent much time in coal mines all over England
  • His work was highly plagiarized, causing him to go bankrupt and into debtor’s prison
  • Bestowed the Wollaston Medal by the Geological Society of London in 1831
  • Known as the father of English geology

Modern Tools

Fun Paper Friday

This week we go over a paper that discusses one of Shannon’s favorite sayings: All Models Are Wrong, but Some Are Useful, Field (2015)

Three main points:

1) “Given all models are wrong, what we really hope is that any new model is more useful than its predecessors and that the value added exceeds the total development costs.”

2) “It still remains to be seen how long we will need to wait for definitive results on usefulness under various conditions.”

3) “Not only are all models wrong, but their relative usefulness varies depending on location and the specific loss metric of interest.”

Contact us:

Showwww.dontpanicgeocast.com@dontpanicgeo – show@dontpanicgeocast.com

John Leemanwww.johnrleeman.com@geo_leeman

Shannon Dulin@ShannonDulin


New episode!

Leave a Comment

Filed under Uncategorized

Episode 2 – If you’re doing geology in pen, you’re just not doing geology right

This week we discuss field tools – everything from clothing to pens and notebooks! Shannon panics due to Earth’s close encounter with an asteroid and John talks about the smell after rainstorms. We want to hear your feedback!

  • John has been playing more with radar during the northeast blizzard.
  • Shannon has been keeping an eye on asteroid 2004 BL86 as it passed near the Earth Monday. There are already a lot of neat radar images coming from this event.
  • Shannon is also planning her first class field trip for a field methods class.

Field Packs

  • People use everything, backpacks, fanny packs, etc.
  • John has a holster thing like SWAT teams. Looks a little like a weapon holster though, so be careful. (He also can’t find anyone that still sells them.)
  • Shannon uses a wait-pack.
  • John and Shannon use stretchy belts to hold their hammers.
  • Lots of folks use their hammer as a ruler in the field.

Clipboards

Field Clothing

  • Clothing tech revolutionized geology!
  • Drilling with quick-dry pants vs. carrying rainsuits that you sweat in anyway.
  • All drab colors! Consider wearing a safety vest!
  • Hat suggestions? Maybe we should go back to full academic dress?
  • Polarized sunglasses are a must. Just beware that they can alter the color of things!

Field Notebooks

  • Traditional Write-in-the-Rain/Field books. Shannon doesn’t like these because of pencil writing quality.
  • Extras in the back of different series of notebooks can be problematic
  • Notebook closures: Binder clip, rubberband, or elastic over notebook
  • If you’re really into this stuff, you would probably like the Pen Addict Podcast.
  • Do you attach your pen/pencil to your field book?
  • Pocket protectors, John has the stealth.

Writing Instruments

  • 0.5 mm pencils for writing in the field books
  • For sketching/musing Palomino Blackwing 602
  • Shannon misses the Zebra301 ultra

Compasses/Hand-lenses

  • Bruntons are the standard, with really no substitue
  • Handlens are now available with led lights (and uv if you’re that into it)
  • iPads vs. regular topo map concerns
  • Battery life
  • Weather resistance
  • Overheating
  • GPS (integrated or separate)
  • Does it take too much away from basic navigation skill development?

#Fun Paper Friday

Contact us:

Showwww.dontpanicgeocast.com@dontpanicgeo – show@dontpanicgeocast.com

John Leemanwww.johnrleeman.com@geo_leeman

Shannon Dulin@ShannonDulin

Any opinions, findings, and conclusions or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the views of our employers or funding agencies.


New episode!

2 Comments

Filed under Uncategorized