Geology 101 with Willsey, Episode #24: Explaining Strike and Dip

Here in episode no. 24 we explain the often confusing concepts of strike and dip. In future episodes, we will learn how to measure strike and dip.
New to geology, want to learn some basic concepts, or just need a geology refresher? Join geology professor Shawn Willsey for this new series as he presents the same lectures as his GEOL 101 (Physical Geology) course. These videos are for everyone.
Support these educational videos! Your generous support allows me to create more videos. Send support via:
PayPal: www.paypal.com...
Buy Me: buymeacoffee.c...
Venmo: @shawn-willsey
or click on the "Thanks" button above.
Or a good ol' fashioned check to:
Shawn Willsey
148 Blue Lakes Blvd N
#141
Twin Falls, ID 83301
WIllsey website: www.willseygeo...
Willsey merch store: geologyexplain...

[@shawnwillsey]

Please LIKE and SUBSCRIBE. I also appreciate your continual support of these geology education videos. To do so, click on the "Thanks" button just above (right of Download button) or by going here: www.paypal.com/donate/?hosted_button_id=EWUSLG3GBS5W8 Or: www.buymeacoffee.com/shawnwillsey

[@causewaykayak]

Every one a winner! I hope that making these episodes isn't chewing into your family time too m6ch BUT they are truly excellent. Your growing tribe of geology recruits testifies to that. I for one am very much looking forward to the next one. 👍🏽

[@shawnwillsey]

Thanks. These aren’t too much work to do and I’m happy to hear they help folks.

[@xwiick]

Thanks for all the hard work on these videos!

[@jacquie-h4530]

Thank you again, Shawn. When I started this lesson I was convinced I'd never get the concepts but I got to the quiz and surprised myself. I got the right answer! I stopped my brain panicking and overthinking, cleared a space to picture your diagrams, and just took it back to simple directions. I'm looking forward to the next lesson when you go out into the field to look at rocks!

[@Firebuck]

The visual aids _really_ help with this one. I've googled "define strike geology" before and the answer might as well come back in hieroglyphs -- that's how well I understood it. But now I get it! You're a terrific teacher, Shawn. 👏

[@shawnwillsey]

Thanks for watching. Glad the visuals helped.

[@craighoover1495]

Thanks, I have been a You Tube geology student for the last 4-5 years and never quite grasped these concepts to my satisfaction until now.

[@mbvoelker8448]

Good refresher to my 40 year old GEO 101 memories.

[@professorsogol5824]

In your quiz, you told us the strike is North East/South West (or azimuths 45/225). Does geology use both numbers (one compass bearing and its 180 degree complement)? If only one number is normally cited, how do you decide which one to use? Northern hemisphere, relative to North, in the southern hemisphere, relative to South?

[@shawnwillsey]

For strike, you can use either direction although there is a convention called right hand rule which determine the preferred strike direction. Look for an upcoming video on this.

[@stevewhalen6973]

Thanks! Good to know when learning how to conceptualize Geological mapping

[@timpointing]

Thanks again. Another easy-to-understand video. I have two questions on this: 1) When describing strike direction in degrees, is there any convention on the numerical range for the strike angle in degrees. For example, a bed which strikes NW-SE could be described as a -45° or it could be 135° (or even 315°!). Is there a convention whereby it is normal to keep the angle in the range 0° to180° or perhaps -90° to +90°? 2a) For clarity, how is the orientation of the symbol for the overturned bed done? For the example symbol, on the slide you showed with the four symbols, does this show a bed whose original "up" is now pointing down to the lower-left or is it down to the upper-right? [As you pointed out in your video, this really is a subject that is inherently "visual" and hard to describe succinctly and clearly!] 2b) Would the dip angle for overturned beds be given as a number >90°

[@oscarmedina1303]

Thank you Shawn.

[@shelleyszulinszky9732]

Makes sense! Thank you ❤️✌️👍

[@filmic1]

Thank you very much. I took a Geography course at Univ. of Calgary many years ago. Though we didn't use the Bruton transit, the professor had laid out stereographic photos of Eastern Slope Rocky Mountains, with stereo graphic magnifiers and showed us on large scale Strikes and Dips. Took a Coursera Geology 'Our Earth It's History, Climate and Processes' Univ of Manchester. (UK.)

[@sandrine.t]

Very nice! Not easy to explain or understand but you did it. And, like you said, visuals really help! The quiz question was simple, I nailed it ;) I can't wait to see how the Brunton compass work in your next video. I'm learning a lot with this series, I love it! :))) Thanks for another excellent lesson, Shawn!

[@hansschleichert7852]

Thanks!

[@raenbow66]

Here we go...I have some making up to do! Thanks so much, Shawn! These classes have meant so much to my understanding!

[@CPaulCounts]

It's been approaching 30 years since I used a Brunton. I'm looking forward to the bonus next episode.

[@geolyn]

Only 30 years? 😁 I'm approaching 50 years and I seem to remember the measuring device was called a clinometer (in the UK). I can't remember what you did with it so I too am looking forward to the next episode!

[@davidk7324]

1978 is the last time I shot an azimuth on a day and night compass course. GI lensatic for my EFMB. Looking forward to the Brunton demo.

[@CPaulCounts]

@@geolyn 😁

[@tamar182]

Thank you so much, Dr. Willsey! I always enjoy watching your videos! Now, you've got to come to Hawaii to film a Roadside video!

[@shawnwillsey]

I’ll be there in Jan/Feb on Big Island. Any special roadcuts in mind?

[@tamar182]

@ Excellent! If you can get anywhere near Isaac Hale Beach Park, it would be interesting to see. Also there are some interesting roadcuts along Saddle Road as well.

[@jimscheltens2647]

Glad to finally learn what these terms mean.

[@JanClancey]

This will require re watching 😊 but you explain so clearly thank you Shawn

[@leenappeldoorn6075]

Bedankt 👍🏻

[@PlantaVeganas]

hi teacher i'm starting with structural geology, and understand all, very helpful, thanks so much :]

[@3xHermes]

Thx!

[@Dragrath1]

You have exposed a weakness of mine here probably will need to rewatch this one again as the compass directions are confusing my brain

[@codyedwards6922]

I got the notification at 11:11. Make a wish Willsey.

[@johncooper4637]

I assume that if the rock layers have been compressed horizontally that you take the general direction of the compression.

[@charlesward8196]

I could not resist getting a Made in USA vintage Brunton Pocket transit. It is in excellent condition, and I bought it for $99.00 plus shipping on eBay last week.

[@shawnwillsey]

Nice score! Enjoy.

[@dougsundseth6904]

When reporting strike, do you use magnetic or true direction? I assume true, but that does implicate the use of magnetic corrections by location, which I've found to be a bit tricky to teach when teaching orienteering.

[@stevewallace9124]

Have you had the opportunity to look at Wendover, Utah’s Volcano Peak? It is a very strange and different mountain that has features I have never seen in other volcanos.

[@shawnwillsey]

I am not familiar with Volcano Peak near Wendover. Do you mean Pilot Peak?

[@stevewallace9124]

@@shawnwillsey It is a few miles south of Pilot. It is a very dramatic peak that should be in a “Lord of the Ring” type movie.

[@stevewallace9124]

@@shawnwillsey is there a place I can send you a few pictures of it?

[@SylasMoon]

thank you, my teachers didnt explain this very well

[@mechabubba]

youtube suggestions goin wild. not my major, not my college. gonna see if i can make heads or tails of this

[@sudazima]

roughly how many episode till we get to GEOL102?

[@shawnwillsey]

Oh boy. I haven't committed to this yet. There are still a dozen or more episodes left in the GEOL 101 series. GEOL 102 at my college is Historical Geology, which covers the Earth's history and the evidence.

[@greedygringoprospecting6941]

you live in or near orange county ca. i look for gold. you should see the creek bed i go to. intrusive rock all over. you name its there.

[@adairjanney7109]

I want you to explain the weird strips of land in Pocatello/Chubbuck near the wind farms, if you dont know what I am speaking of I can provide coords, in fact if it lets me ill edit this and add those if you see this anyway 42°48'24"N 112°43'54"W

[@owenlindblom6981]

I think what you are seeing are buried pipeline scars.

[@jefferyporter9645]

Hello everyone

[@J0hnC0ltrane]

I chose correctly but then was over thinking it a bit.

[@skyedog24]

🧭 🔨

[@professorsogol5824]

Please do not fail to show us how to measure strike and dip with a cell phone. Brunton compasses are expensive, but all of us amateur geologists looking to up our game have cell phones. Then our only problem when out in the field is do we have a signal?

[@wheezer324na3]

Thanks!