Latest / PlanetGeo: The Geology Podcast / Why don't beaches erode quickly? Plus an interesting beer question (GeoShort)

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Why don't beaches erode quickly? Plus an interesting beer question (GeoShort) · PlanetGeo: The Geology Podcast

• 0:03
  SPEAKER_01: Welcome to Planet Geo, the podcast where we talk about our amazing planet, how it works, and why it matters to you.
• 0:13
  SPEAKER_01: Today we're doing another Geo short, and this is another listener question.
• 0:16
  SPEAKER_01: And this question comes from Tom, and it comes in two parts.
• 0:20
  SPEAKER_01: Part A is Chris, what's your favorite beer to drink while looking at the Grand Tetons?
• 0:26
  SPEAKER_01: Which is a great question to begin with.
• 0:28
  SPEAKER_01: We'll come to that.
• 0:29
  SPEAKER_01: We'll come to that one later.
• 0:30
  SPEAKER_01: Part B was why don't beaches erode quickly?
• 0:34
  SPEAKER_01: Which is a really kind of interesting and thought-provoking question.
• 0:37
  SPEAKER_01: And we're going to answer this in two ways.
• 0:39
  SPEAKER_01: Chris, you and I have not compared our answers.
• 0:42
  SPEAKER_01: So, Chris, what is your answer to why don't beaches erode quickly?
• 0:46
  SPEAKER_00: Uh, my take on this is they do.
• 0:49
  SPEAKER_00: Beaches erode very quickly.
• 0:51
  SPEAKER_00: Beaches are made up of loosely packed sand.
• 0:54
  SPEAKER_00: Unconsolidated means the sand grains are not cemented and compacted together at all.
• 0:59
  SPEAKER_00: Um, and so beaches do erode quickly.
• 1:02
  SPEAKER_00: Uh, you can have beaches that seem to be a staple, they're there forever.
• 1:07
  SPEAKER_00: You have this beachfront property and and it's just there, but then all it takes is a 50-year storm, a hundred-year storm, or even worse than that, and all of a sudden that beach dramatically changes.
• 1:18
  SPEAKER_00: We see this up and down the east coast of the United States when the hurricanes come in and they gotta then do beach nourishment, which Jesse, that's an episode for later on, a full episode.
• 1:27
  SPEAKER_00: So we see this now and and along the shores of the Great Lakes.
• 1:30
  SPEAKER_00: The Great Lakes are monumentally high right now.
• 1:33
  SPEAKER_00: We're seeing record highs with this.
• 1:35
  SPEAKER_01: Oh, you mean water levels are really high right now in the Great Lakes?
• 1:38
  SPEAKER_01: Oh, interesting.
• 1:38
  SPEAKER_01: Okay, I didn't know that.
• 1:39
  SPEAKER_00: They are extremely high right now, they have been for a few years now, and our beaches are being eroded, and a lot of people are suffering from it.
• 1:47
  SPEAKER_00: And if this erosion, anything that happens in geology that happens in a day, a week, a month, and even on the scale of years, that's fast.
• 1:56
  SPEAKER_00: And and so, yeah, things have stayed the same for a long time.
• 1:59
  SPEAKER_00: All of a sudden, one or two years change, and now all of a sudden the whole beach landscape has changed.
• 2:04
  SPEAKER_00: So I would say beach erosion happens fast, it can happen fast.
• 2:11
  SPEAKER_01: Interesting.
• 2:11
  SPEAKER_01: Yeah.
• 2:12
  SPEAKER_00: Okay, your turn, Jeff.
• 2:13
  SPEAKER_01: So when I read this question, I thought the same as you beach erosion does happen quickly, but I kind of thought about it from a different perspective.
• 2:19
  SPEAKER_01: So, and the long term, you know, beaches are kind of stable, but an individual sand grain is moving all over the place.
• 2:26
  SPEAKER_01: So I thought of a longshore current, which if you ever stand on a pier, look in one direction of the pier, look on the other side of the pier, you're gonna see a difference in the amount of sand on one side or the other.
• 2:37
  SPEAKER_01: And the reason for that is that sand is being transported along the beach, and that's because waves don't always hit the beach head on, they often hit at an angle.
• 2:48
  SPEAKER_01: So when they hit at an angle, they're moving sand grains up kind of in an angular direction.
• 2:52
  SPEAKER_01: And then when that water flows back downhill, it moves it straight downhill.
• 2:57
  SPEAKER_01: So that up at an angle and down straight, up at an angle, down straight means that sand grains are moving in one direction due to wave after wave after wave after wave.
• 3:07
  SPEAKER_01: And if you have a seasonal wind pattern, like in the, you know, if you have typically winds from the west, they might hit the beach at an angle and move sand in one direction.
• 3:16
  SPEAKER_01: So you put a pier in there and it's gonna pile up sand on one side, it's gonna deplete sand from the other side.
• 3:22
  SPEAKER_01: That's a long shore current.
• 3:23
  SPEAKER_01: The one-sentence answer to this question was that actually beaches do erode very quickly, they just erode side to side instead of up and down pretty quickly.
• 3:33
  SPEAKER_00: Yeah.
• 3:33
  SPEAKER_00: So as sand gets moved downstream, sand also gets deposited in its place.
• 3:38
  SPEAKER_01: Exactly.
• 3:39
  SPEAKER_01: Exactly.
• 3:39
  SPEAKER_01: Yep.
• 3:40
  SPEAKER_00: So as it gets eroded, new stuff gets deposited in its place, and it establishes this equilibrium until a gigantic storm comes along and just disturbs that whole equilibrium.
• 3:50
  SPEAKER_01: Yeah.
• 3:50
  SPEAKER_01: So when you walk out, I mean, uh most of us, I mean, many, many of us probably go to beaches for like calm vacations, you know, stable vacation.
• 3:58
  SPEAKER_01: So when you're sitting on a beach, you know, having your little daiquiri or whatever, and you're thinking, wow, the world is so calm.
• 4:03
  SPEAKER_01: Picture that one little sand grain, and it is in a frantic frenzy moving all over the place.
• 4:08
  SPEAKER_01: It is not a stable environment for that one sand grain.
• 4:11
  SPEAKER_00: I so you're sitting there, you're sitting on the beach, Jesse.
• 4:14
  SPEAKER_00: You got Tess right next to you, and you guys have an enchanted moment.
• 4:17
  SPEAKER_00: You're watching the sunset.
• 4:19
  SPEAKER_00: No, you're not.
• 4:20
  SPEAKER_00: You're watching sand come up the beach, rolling right as the as the white caps crash up along the beach, kid.
• 4:26
  SPEAKER_00: They get your ankles wet and so on.
• 4:27
  SPEAKER_00: You're watching little sand grains say they do this little zigzag triangular pattern back and forth and off that little sand grain goes down.
• 4:34
  SPEAKER_00: You're following that.
• 4:35
  SPEAKER_00: I know what you're doing.
• 4:35
  SPEAKER_00: Poor Tess.
• 4:36
  SPEAKER_01: Yeah, totally.
• 4:37
  SPEAKER_01: You know, I'm thinking, wow, that little sand grain is moving all over the place.
• 4:41
  SPEAKER_01: I wonder what happens if we build a little if we build a little pier right here, you know.
• 4:45
  SPEAKER_01: Yeah, yeah, for sure.
• 4:46
  SPEAKER_00: I think actually this is a topic, a bigger topic for later on.
• 4:49
  SPEAKER_00: Absolutely.
• 4:50
  SPEAKER_01: I do.
• 4:50
  SPEAKER_01: I agree.
• 4:51
  SPEAKER_01: Uh, so great question, Tom, and we're gonna end it here.
• 4:54
  SPEAKER_01: Chris.
• 4:54
  SPEAKER_00: Hold on, we're not wrapping this up.
• 4:56
  SPEAKER_00: We've got to answer the second part.
• 4:57
  SPEAKER_01: That's right.
• 4:57
  SPEAKER_01: That's right.
• 4:58
  SPEAKER_01: Don't let me forget that.
• 4:59
  SPEAKER_01: Okay.
• 4:59
  SPEAKER_01: So, Chris, what is your favorite beer to drink while looking at the Grand Detons?
• 5:04
  SPEAKER_00: You know what, Jesse?
• 5:05
  SPEAKER_00: I'm not gonna answer that before you do.
• 5:07
  SPEAKER_00: I am gonna throw it back to you.
• 5:09
  SPEAKER_00: Go, because I'm gonna judge you.
• 5:10
  SPEAKER_01: Yeah, of course you are.
• 5:12
  SPEAKER_01: So, my favorite beer to drink is it's gonna be a light beer because I've usually been on a long day hike after that, and there's nothing better than an ice cold, you know, light beer when you're sitting there after a long day's hike and hard work.
• 5:26
  SPEAKER_01: I'm gonna go with like uh a narraganset or a PBR.
• 5:30
  SPEAKER_01: I know that's like super hipster, super stereotypical, but that's what I'm gonna go with.
• 5:34
  SPEAKER_00: Well, I I have to stop doing this with you after this.
• 5:37
  SPEAKER_00: This is our last episode.
• 5:39
  SPEAKER_00: Okay.
• 5:39
  SPEAKER_00: I'm done.
• 5:40
  SPEAKER_01: All right.
• 5:40
  SPEAKER_01: What about you?
• 5:41
  SPEAKER_01: What about you?
• 5:42
  SPEAKER_00: You're looking at the Tetons.
• 5:44
  SPEAKER_00: Life is short.
• 5:45
  SPEAKER_00: I'm drinking a hazy.
• 5:46
  SPEAKER_01: Hazy IPA.
• 5:47
  SPEAKER_01: Okay, that's a good one.
• 5:48
  SPEAKER_01: A hazy IPA.
• 5:49
  SPEAKER_01: That's a good one.
• 5:49
  SPEAKER_01: Oh, yeah, for sure.
• 5:50
  SPEAKER_01: You got a favorite brewery in Jackson Hole to go to?
• 5:52
  SPEAKER_00: I mean, I really do.
• 5:54
  SPEAKER_00: Uh, I like the Grand Teton Brewing Company, which is on the other side of the Tetons in Idaho.
• 5:58
  SPEAKER_00: Okay.
• 5:59
  SPEAKER_00: Um, it's one of my favorites.
• 6:01
  SPEAKER_00: I also really, really like the Snake River Brewing Company.
• 6:03
  SPEAKER_00: I like them both.
• 6:04
  SPEAKER_00: Okay, here we go.
• 6:05
  SPEAKER_00: In Jackson Hole.
• 6:05
  SPEAKER_00: There we go.
• 6:06
  SPEAKER_01: There's there's your answer, Tom.
• 6:08
  SPEAKER_01: All right, and with that, that's a wrap for the Geo Short.
• 6:10
  SPEAKER_01: Tom, thanks for your questions.
• 6:12
  SPEAKER_01: And uh everybody else, keep them coming.
• 6:14
  SPEAKER_01: We love it.
• 6:14
  SPEAKER_00: Yeah, absolutely.
• 6:16
  SPEAKER_01: Take care.
• 6:17
  SPEAKER_00: Cool.