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Sedimentary Maturity - Geology 101: Sediments Part 2 · PlanetGeo: The Geology Podcast

• 0:01
  SPEAKER_00: 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_00: Hi folks, sediments part two coming at you here.
• 0:16
  SPEAKER_00: We are excited to uh bring you some more in our Camp Geo series from the Camp Geo Mobile app.
• 0:22
  SPEAKER_00: Chris and I talking about sediments.
• 0:23
  SPEAKER_00: This is the second part, second episode of our six-part series on sediments, chapter two in the Camp Geo Mobile app.
• 0:30
  SPEAKER_00: Also on the Camp Geo Mobile app, you can get access now to the Roadside Geology of Colorado audiobook, as well as Colorado Rocks, which is something you're looking for, a little more intro level book or something that's a little bit shorter than the Roadside Geology, a little bit less jargon.
• 0:46
  SPEAKER_00: That's your ticket.
• 0:47
  SPEAKER_00: If you're interested in Colorado, if you're heading there anytime soon, go to the Camp Geo Mobile app now and purchase it.
• 0:53
  SPEAKER_00: Um and let us know what you think.
• 0:55
  SPEAKER_00: We're interested in how this trial run resonates with our geologically inclined listener base.
• 1:00
  SPEAKER_00: So let us know and uh sediments coming at you.
• 1:08
  SPEAKER_00: Christopher.
• 1:09
  SPEAKER_01: Hey Jesse, how are you doing?
• 1:11
  SPEAKER_01: Or Dr.
• 1:12
  SPEAKER_01: Remink, doing all right?
• 1:13
  SPEAKER_00: There we go.
• 1:14
  SPEAKER_00: Abuse proper respect, please.
• 1:16
  SPEAKER_01: I I well, okay.
• 1:18
  SPEAKER_01: I don't know if there's respect in there.
• 1:20
  SPEAKER_01: I told you a long time ago that I would call you Dr.
• 1:22
  SPEAKER_01: Remink once.
• 1:23
  SPEAKER_01: And now I'm doing it all the time.
• 1:25
  SPEAKER_01: I know.
• 1:26
  SPEAKER_01: How unfortunate for you.
• 1:27
  SPEAKER_00: And I don't know how I feel about that.
• 1:30
  SPEAKER_00: All right, man.
• 1:32
  SPEAKER_00: We are in chapter two, sedimentary rocks, episode two.
• 1:35
  SPEAKER_00: Where are we coming from and where are we going?
• 1:37
  SPEAKER_01: Yeah.
• 1:38
  SPEAKER_01: So last episode, episode one, we talked about why sedimentary rocks are important.
• 1:42
  SPEAKER_01: We then talked a little bit about the three categories of sedimentary rocks, and then we finished off the episode with where does the sediment come from that form sedimentary rocks?
• 1:53
  SPEAKER_01: And specifically, we're talking about weathering, and we got a little bit into the two types of weathering, mechanical and chemical weathering.
• 2:00
  SPEAKER_01: Today, it's really a continuation of that because what happens to the sediment after it's been weathered.
• 2:07
  SPEAKER_01: So, really, today we're going to talk about the process of erosion, the process of deposition, and then finally the process of lithification.
• 2:16
  SPEAKER_01: That's where we're going today.
• 2:17
  SPEAKER_00: Yeah, and this is just we can distill it down into transporting sediment and dumping sediment somewhere.
• 2:23
  SPEAKER_00: And this is really the this is kind of the meat of sedimentary rocks.
• 2:27
  SPEAKER_00: This is how we look at sedimentary rocks and determine how they formed, where they formed, what the world looked like back in time when that sedimentary rock formed.
• 2:35
  SPEAKER_00: So this is kind of the meat of sedimentary rocks.
• 2:38
  SPEAKER_00: And as we move forward through this, after this, we'll be talking about specific types of sedimentary rocks.
• 2:43
  SPEAKER_00: That's right.
• 2:43
  SPEAKER_00: So erosion.
• 2:44
  SPEAKER_00: We covered weathering.
• 2:46
  SPEAKER_00: Now we're picking up with erosion, which is the close cousin to weathering, which is actually moving sediment now, right?
• 2:52
  SPEAKER_00: Like we always in geology, we always say weathering and erosion, but they're two very related processes, but they are different.
• 2:58
  SPEAKER_01: Yeah, that's right.
• 2:59
  SPEAKER_01: I I think that's an important thing.
• 3:01
  SPEAKER_01: Um, I catch myself, I've been teaching geoscience for a long time, you know, and uh I think about 150 years by last count.
• 3:08
  SPEAKER_01: Yeah.
• 3:09
  SPEAKER_01: I do it all a lot, and I I try not to.
• 3:11
  SPEAKER_01: I I try to be deliberate about drawing the line between what is the process of weathering and what is the process of erosion.
• 3:18
  SPEAKER_01: So last episode we talked that weathering is the breakdown of rocks, and there are two ways of doing that.
• 3:24
  SPEAKER_01: And then what happens to it after it gets broken down?
• 3:27
  SPEAKER_01: That's erosion.
• 3:28
  SPEAKER_01: The sediment gets moved, it gets transported, and that is the process of erosion.
• 3:34
  SPEAKER_00: Yes, and we touched on this last episode, but there are many different agents of erosion.
• 3:38
  SPEAKER_00: Wind, we talked about you know feeling sand or dust-sized particles blowing against your ankles on a really windy day.
• 3:45
  SPEAKER_00: Streams are by far the most important erosion, so streams move a lot of sediment.
• 3:51
  SPEAKER_00: Glaciers actually move sediment as well.
• 3:53
  SPEAKER_00: They sculpt the landscape and move sediment.
• 3:55
  SPEAKER_00: And actually, we've talked about this on our Planet Geo podcast.
• 3:58
  SPEAKER_00: Longshore currents do this too.
• 4:00
  SPEAKER_00: There is sand and material being moved up and down beaches by wave action and the directionality of wave action.
• 4:07
  SPEAKER_00: It's really a cool process, yeah.
• 4:08
  SPEAKER_01: Lawsuits have been brought to court over longshore currents and what who who stole my sediment, you know.
• 4:15
  SPEAKER_00: Yes, exactly.
• 4:16
  SPEAKER_01: Yeah, you know, when you were just talking about this, it brought up a something that reminded me of in my own classes.
• 4:23
  SPEAKER_01: Um, when I ask my students, what do you think the most important agent of erosion is, and I'll list them streams, wind, glaciers, longshore currents, and so on.
• 4:33
  SPEAKER_01: Students from Michigan almost always say glaciers.
• 4:36
  SPEAKER_01: And I get it.
• 4:37
  SPEAKER_00: Oh, yeah.
• 4:37
  SPEAKER_01: You know, because the everything that we have at the surface here in Michigan, all of the inland lakes, all the sediment at the surface, the skin of our crust, it's all glacial in origin.
• 4:48
  SPEAKER_01: And so, yeah, Michigander students always say glaciers.
• 4:53
  SPEAKER_01: But it's not streams by far, it's not even really a close call for second place.
• 4:59
  SPEAKER_01: Streams, rivers move more sediment than any other agent of erosion.
• 5:04
  SPEAKER_00: Yeah, and I think for the purposes of geology and looking back at our planet's history, wind, streams, glaciers, longshore currents, they all deposit sediment in a different manner.
• 5:13
  SPEAKER_00: So we can look at sedimentary rocks and determine which of those agents moved that sediment most.
• 5:19
  SPEAKER_00: And so we can sort of look back and see these processes in the rock record, which is kind of you know what attracts us to geology for sure and why sedimentary rocks are interesting.
• 5:28
  SPEAKER_00: So once we move the stuff, that gets deposited.
• 5:32
  SPEAKER_00: We need to deposit the sediment, aggregate it somewhere so that it can eventually become a rock.
• 5:37
  SPEAKER_00: So how does that work, Chris?
• 5:39
  SPEAKER_01: Well, water is very discriminating.
• 5:42
  SPEAKER_01: It can only carry, according to how fast the water's moving, or what we refer to as the energy of the water, water can only move certain sized or certain masses of particles, right?
• 5:56
  SPEAKER_01: And in that way, when we see a sedimentary rock that has certain particle sizes, we're able to get a lot of information from just that little cursory glance at it.
• 6:07
  SPEAKER_01: Like what was the energy of deposition?
• 6:10
  SPEAKER_01: You know, because glaciers, they don't do this, right?
• 6:13
  SPEAKER_01: Glaciers, when they move sediment, they can move a boulder the size of a house as easily as it can move a grain of sand.
• 6:19
  SPEAKER_01: They don't discriminate in the way that water does.
• 6:22
  SPEAKER_01: Water can only carry and then deposit what it's capable of doing it.
• 6:27
  SPEAKER_00: Exactly.
• 6:28
  SPEAKER_00: And the first image in your stack shows this at a very rough scale.
• 6:32
  SPEAKER_00: And you can imagine this, right?
• 6:33
  SPEAKER_00: Picture a mountain stream.
• 6:35
  SPEAKER_00: I don't know if you've ever hiked in the mountains.
• 6:36
  SPEAKER_00: You can imagine what you were walking along, but there's big boulders in the mountain stream.
• 6:40
  SPEAKER_00: We have this in Pennsylvania.
• 6:41
  SPEAKER_00: You go up high, and the little tiny streams have big boulders in them.
• 6:44
  SPEAKER_00: That's because when those streams flood, they can move those big boulders.
• 6:48
  SPEAKER_00: Once you get down into the still big streams down in the river valleys, but they're relatively slow moving.
• 6:55
  SPEAKER_00: Those can't really move boulders very easily.
• 6:57
  SPEAKER_00: So there's a lot more smaller particles being moved by the Mississippi River than there is by some high mountain stream.
• 7:04
  SPEAKER_00: And that's in part due to the energy of the water, due to the topography as well.
• 7:09
  SPEAKER_00: But that schematic that is image one kind of shows this process in action.
• 7:14
  SPEAKER_01: Right on.
• 7:15
  SPEAKER_01: So basically, there's this general saying basically, big particles, if you have big clasts or pieces in a sedimentary rock, that means that that was a very high energy, fast moving environment of deposition, right?
• 7:30
  SPEAKER_01: Moderately sized particles then means a moderate kind of energy, moderate speed, let's say in a river.
• 7:38
  SPEAKER_01: And then if you have very fine-grained clasts or pieces, fragments like dust-sized pieces, those are only allowed to settle out if the water is very calm, quiet, and low, low, low energy, because any kind of turbulence will keep those light, small, tiny sediments lifted and kept in suspension.
• 7:57
  SPEAKER_00: Yeah, basically to get those very tiniest fragments to fall out of suspension, you basically have to be in a completely still water environment, which is usually the deep ocean basin.
• 8:06
  SPEAKER_01: So, in this way, the pieces or the clasts tell us everything that we need to know about the energy in which deposition happens.
• 8:14
  SPEAKER_01: And so, Jesse, can you talk a little bit about then what the maturity of the sediment means?
• 8:19
  SPEAKER_01: Like what does that term refer to?
• 8:21
  SPEAKER_00: Maturity is this term we use to describe basically how the sediment has changed from the source where the weathering happens downstream to where it's ultimately deposited.
• 8:34
  SPEAKER_00: And so a very low maturity sediment will have really angular classs.
• 8:41
  SPEAKER_00: It hasn't been rounded a lot.
• 8:42
  SPEAKER_00: It'll have a wide variety of sizes of class.
• 8:45
  SPEAKER_00: And image number two in your stack kind of shows two components of this: the sorting and the rounding part of it.
• 8:51
  SPEAKER_00: So upstream in the mountains, you're gonna have angular class, you're gonna have a poorly sorted sediment where there's small pieces and large pieces.
• 8:58
  SPEAKER_00: As you move downstream, as you move out towards something like the Mississippi River or the Amazon River, you're gonna have very well sorted, very rounded particle sizes in there as you move downstream.
• 9:10
  SPEAKER_00: That is the sediment becoming more quote unquote mature.
• 9:13
  SPEAKER_00: As it gets mature, it gets sorted and rounded.
• 9:16
  SPEAKER_01: Okay.
• 9:17
  SPEAKER_01: Can I rephrase that then maybe and put it a different way?
• 9:20
  SPEAKER_00: Definitely.
• 9:21
  SPEAKER_01: Really, I think what you're saying is the maturity is indicative of the degree of transport, right?
• 9:26
  SPEAKER_01: How far it moved.
• 9:28
  SPEAKER_01: It gets more mature the further it moves, right?
• 9:31
  SPEAKER_00: Exactly.
• 9:32
  SPEAKER_00: And images two and three in your stack are both showing this, and they're showing kind of different aspects of this slightly.
• 9:39
  SPEAKER_00: Image number three shows you a couple examples of rocks and what they might look like as you move further in the transport process.
• 9:47
  SPEAKER_00: And so what we mean by sorting is both the size gets sorted, but also the minerals get sorted.
• 9:54
  SPEAKER_00: So you'll move from having a whole bunch of sand grains that are both quartz and feldspar and little pieces of rocks that are all the same size, and you'll move into a place where only quartz is left behind.
• 10:03
  SPEAKER_00: You basically have one mineral in the sediment.
• 10:07
  SPEAKER_01: Think of if I gave you a jar full of Skittles, because I like Skittles, it's really good candy.
• 10:13
  SPEAKER_00: And I said, okay.
• 10:14
  SPEAKER_00: Okay.
• 10:14
  SPEAKER_00: I'll give you the jar of Skittles.
• 10:16
  SPEAKER_00: I don't love Skittles, so I'll give you the jar of Skittles.
• 10:18
  SPEAKER_01: Well, I'm just saying, if I gave the if I gave a jar full of Skittles to anyone and said sort it out, everyone knows what to do.
• 10:24
  SPEAKER_01: You're gonna sort it out into five different piles according to the color, right?
• 10:28
  SPEAKER_01: If I give you a jar full of peas and marbles and sand and said sort it out, everyone again knows what to do.
• 10:36
  SPEAKER_01: You're gonna sort it into three different piles.
• 10:38
  SPEAKER_01: You're gonna have a pile of sand, a pile of marbles, and a pile of peas.
• 10:41
  SPEAKER_01: That's sorting.
• 10:42
  SPEAKER_01: And then when you have a sediment, your rock that is really well sorted, that means that it's got one particle size.
• 10:49
  SPEAKER_01: They all weigh the same thing, and they're probably made up of the same mineral.
• 10:53
  SPEAKER_00: Exactly.
• 10:54
  SPEAKER_00: That's a well-sorted sample.
• 10:56
  SPEAKER_00: So if you're hiking out there, if you're walking along, you're driving past a road cut or something like that, and you see a rock and you see big boulders and they're big sharp angles, those boulders are sitting right next to really tiny pieces of rock in the rock face.
• 11:09
  SPEAKER_00: That did not travel very far because those big boulders would have gotten broken down if it had been transported a very, very long distance.
• 11:17
  SPEAKER_00: And so that's just a really general approach to this, but it's it's very powerful for us.
• 11:22
  SPEAKER_01: But it works, that's right.
• 11:23
  SPEAKER_00: Exactly.
• 11:24
  SPEAKER_01: Okay, so we have done weathering, we've talked then about erosion, removal of the sediment, we've talked about deposition and what that means, and how the deposition tells us the energy in which these particles and these rocks formed.
• 11:38
  SPEAKER_01: The last step in this process then is a term called lithification.
• 11:44
  SPEAKER_01: And lithification is now, all right, we have this sediment that's been deposited in a very specific environment.
• 11:50
  SPEAKER_01: Now we have to turn it into rock.
• 11:52
  SPEAKER_01: And lithification is a two-step process.
• 11:56
  SPEAKER_00: Yeah, I think the best way to think about this is your beach sand.
• 11:58
  SPEAKER_00: You know, you're walking around, it's sand, it's not tied together in any way.
• 12:02
  SPEAKER_00: We need to take that beach sand and make it a rock.
• 12:04
  SPEAKER_00: And so the first step to doing that is compaction.
• 12:07
  SPEAKER_00: You need to compact that down, squeeze out all of the air, all of the water, typically, that's in this sediment, and compact the thing down to reduce the pore size.
• 12:18
  SPEAKER_00: And that usually happens naturally by just adding more sediment on top of what you have already.
• 12:23
  SPEAKER_00: So as you add more sediment into an area, the sediment will sink under its own weight and then continue to sink under the weight of the stuff that's overlying it.
• 12:33
  SPEAKER_00: So that we only see in an active sedimentation environment, a stream bed or the beach, we're only seeing that uncompacted, unlithified top portion.
• 12:43
  SPEAKER_00: If we dig down deeper, we will get into stuff that is more compacted and closer to a rock.
• 12:49
  SPEAKER_01: And sometimes lithification, the part of lithification, compaction, sometimes that can be the only part of the process.
• 12:58
  SPEAKER_01: There isn't the second part of it, which is called cementation.
• 13:00
  SPEAKER_01: We'll get into that in a minute.
• 13:02
  SPEAKER_01: Sometimes rocks are formed strictly by compaction.
• 13:06
  SPEAKER_01: An example of this is like the rock shale, the most abundant clastic sedimentary rock.
• 13:11
  SPEAKER_01: And shale is made up of dust-sized pieces of rock, of weathered rock.
• 13:18
  SPEAKER_01: And so it's only compacted.
• 13:21
  SPEAKER_01: There's no cement holding it together, there's no glue holding these grains together.
• 13:26
  SPEAKER_01: So shale is soft, it's crumbly.
• 13:29
  SPEAKER_01: I always refer to it as kind of a wimpy rock because it doesn't stand up well to the w rigors of you know erosion and so on.
• 13:37
  SPEAKER_01: It's the first to break down because it's only compacted.
• 13:40
  SPEAKER_00: Exactly, Chris.
• 13:41
  SPEAKER_00: And compaction reduces this pore space and basically squeezes all of the air and water out of the rock.
• 13:47
  SPEAKER_00: So fluids cannot really circulate easily through this sediment.
• 13:50
  SPEAKER_00: It is now compacted and much closer to being an actual rock.
• 13:55
  SPEAKER_01: And that makes shale then very easy to spot in the field.
• 13:59
  SPEAKER_01: I think everybody at this point knows, you know, how you and I really got to know each other very well for the first time was on this field course that I teach out west every summer.
• 14:07
  SPEAKER_01: You know, and uh so I always use this term called roadside geology.
• 14:12
  SPEAKER_01: I stole the term from this series of books, you know, that it explains like the geology of each state.
• 14:17
  SPEAKER_00: It's called roadside geology.
• 14:19
  SPEAKER_00: Those are great books, by the way, if you're just driving around and you need to know why's that mountain is there, they're great books.
• 14:24
  SPEAKER_01: Yeah, so good.
• 14:25
  SPEAKER_01: So I I use this term a lot then in my classes, uh just roadside geology, which I call geology at 70 miles an hour.
• 14:32
  SPEAKER_01: You know, we don't always have to stop, you know, we don't have to stop and get out to know what we're looking at.
• 14:38
  SPEAKER_01: We can fly down the road here at 70 miles an hour and look out of the windows of the bus and see, oh, there's shale.
• 14:44
  SPEAKER_01: And how do we know that that's shale?
• 14:46
  SPEAKER_01: Because it's soft, it's crumbly, and you can just see that it tends to form slopes rather than cliffs.
• 14:54
  SPEAKER_01: And so that's just that's what I call roadside geology is geology at 70 miles an hour, looking out a van window or a bus window.
• 15:01
  SPEAKER_00: Yes, that's good.
• 15:02
  SPEAKER_00: I mean, I remember sitting there as a high school student, and I think you always had the uh you had the intercom, walkie-talkie, that you would talk to while you're driving the bus with one hand and you're lecturing about geology with the other.
• 15:12
  SPEAKER_00: Oh, it's great.
• 15:13
  SPEAKER_00: That was the way I that was the way I learned geology back when I was a young punk.
• 15:17
  SPEAKER_00: That is roadside geology, right?
• 15:20
  SPEAKER_00: Indeed.
• 15:20
  SPEAKER_00: Okay, so the last process that typically happens, doesn't need to happen though, is cementation.
• 15:25
  SPEAKER_00: And this is just locking the little pieces of rocks or minerals together in the sediment.
• 15:30
  SPEAKER_00: And this can happen really kind of two ways.
• 15:32
  SPEAKER_00: Some minerals, like quartz, for instance, during compaction, when we compact quartz, it will actually dissolve itself and it'll reprecipitate and it'll bond itself together.
• 15:42
  SPEAKER_00: So quartz grains can kind of self-bond one another together without any other fluids bringing in material.
• 15:49
  SPEAKER_00: But the other way, and and sometimes the more common way, Chris, is to have fluid flowing through here, right?
• 15:54
  SPEAKER_01: Right on.
• 15:55
  SPEAKER_01: If you have water circulating through the rock, through the pore spaces, in between the grains, and that water has salts dissolved in it.
• 16:05
  SPEAKER_01: Things like what you just alluded to, silica or dissolved quartz, calcium carbonate, which is the mineral calcite, or iron oxides, these things that are dissolved in the water.
• 16:16
  SPEAKER_01: As the water circulates through these grains and among the pore spaces, it will precipitate these salts in the spaces, therefore, like binding or gluing the rock together.
• 16:28
  SPEAKER_01: And that's called cementation.
• 16:29
  SPEAKER_00: Exactly.
• 16:30
  SPEAKER_00: And so the last image in your stack shows these two processes, compaction and cementation, in a kind of schematic view.
• 16:37
  SPEAKER_00: The top image is the deposition, the sediment that it looks like when it's not a rock, it's just a sediment.
• 16:43
  SPEAKER_00: And then the bottom image shows compaction, squeezing these things together, and then cementation, where the teal color is this new cement that is being precipitated between the grains and locking them together.
• 16:54
  SPEAKER_00: At that stage, we have a rock.
• 16:56
  SPEAKER_00: It is now a sedimentary rock.
• 16:58
  SPEAKER_01: You know, out in the southwestern part of the United States, Arizona, Utah, places like this, there is a lot of red sandstone.
• 17:06
  SPEAKER_01: And it's bright red.
• 17:08
  SPEAKER_01: It's you know, it's referred to as like the painted desert.
• 17:11
  SPEAKER_01: It's gorgeous.
• 17:12
  SPEAKER_01: And the red comes from the cement holding the sand grains together.
• 17:16
  SPEAKER_01: It's an iron oxide, and it turns various shades of orange and brown and things like this when it oxidizes.
• 17:23
  SPEAKER_01: And it's surprisingly, it's a only a little bit of iron oxide that can stain the whole rock red.
• 17:30
  SPEAKER_01: Real quick, you can see this right when you're walking down a sidewalk or you're on a road, and those brown stains that we see on the sidewalk, those are from iron oxide minerals that are in the concrete that then it gets wet when it rains and so on, and the water runs off a certain direction.
• 17:50
  SPEAKER_01: So these things all kind of tail off in one direction.
• 17:53
  SPEAKER_01: That's a great example, though, of one little grain in the cement that can stain a whole bunch of rock around it.
• 18:00
  SPEAKER_00: Yeah, you know what's interesting, Chris.
• 18:01
  SPEAKER_00: We don't have in Pennsylvania, we don't have a ton of that iron staining on the sidewalks just because of the places that the concrete fill comes from doesn't have a lot of iron oxides, but most places you will typically have at least some in there.
• 18:13
  SPEAKER_01: Interesting.
• 18:14
  SPEAKER_01: Never thought about that.
• 18:15
  SPEAKER_01: One other thing about the whole lithification process that I want to just maybe paint an analogy, right?
• 18:20
  SPEAKER_01: If I take a Dixie cup, just a little plastic Dixie cup, right?
• 18:24
  SPEAKER_01: And I fill it up with just sand, okay, and I I compact it, okay, with my hand.
• 18:30
  SPEAKER_01: I fill it up and I compact it, I get as much in there as I can, and I take a pin and I poke holes in the bottom of the cup.
• 18:37
  SPEAKER_01: Okay.
• 18:38
  SPEAKER_01: Holes are small enough, the sand doesn't come out, but I pour water then through that cup.
• 18:43
  SPEAKER_01: I pour it, let the water seep out, it'll drip out of the holes at the bottom and so on.
• 18:47
  SPEAKER_01: And I pour a whole bottle of water through that.
• 18:50
  SPEAKER_01: And then I just take that cup and I set it on a counter.
• 18:54
  SPEAKER_01: I take another cup, do the same thing.
• 18:56
  SPEAKER_01: Okay, fill it up with sand, compact it, poke holes in the bottom.
• 18:59
  SPEAKER_01: This one though, I'm gonna pour salt water through.
• 19:02
  SPEAKER_01: And I'm gonna just do this very carefully, pour it, get it all to go through, let it sit on the counter, come back after a week, when everything is dried up, there's no more water in the cup.
• 19:12
  SPEAKER_01: I go back to cup number one and I tear the plastic away, and I have a handful of sand, right?
• 19:17
  SPEAKER_01: It's it's loose, it's not consolidated, it's not a rock, it's just loose sediment.
• 19:22
  SPEAKER_01: But I take that cup number two that I poured salt water through, and I tear the cup away, and I now have a cup-shaped lump of sand in my hand.
• 19:31
  SPEAKER_01: I have a rock because it's been compacted, and the salt that was in the water is binding the sand grains together, so that rock is also cemented.
• 19:41
  SPEAKER_01: So you have to have salty water to cement the rock.
• 19:45
  SPEAKER_00: That's a great analogy, Chris.
• 19:47
  SPEAKER_00: So, to kind of summarize this episode, we talked about weathering.
• 19:50
  SPEAKER_00: Well, we talked about that last episode really.
• 19:52
  SPEAKER_00: We've picked up from weathering, and we talked about erosion.
• 19:55
  SPEAKER_00: We talked about how sediment gets mature the further from the source it is, so the longer the distance of transport, the more mature the sediment becomes.
• 20:05
  SPEAKER_00: And a few of those images in your stack show that process schematically.
• 20:09
  SPEAKER_00: We then went to deposition, how rocks are formed, where they're formed, where the sediment is actually accumulated and deposited, and then wrapped it up with lithification, which is this process of taking loose sediment and forming it into a rock.
• 20:22
  SPEAKER_00: And your analogy at the end, Chris, nailed it.
• 20:24
  SPEAKER_00: You need to do compaction and cementation, and then we have a rock.
• 20:28
  SPEAKER_00: So that's a wrap on chapter two, episode two.
• 20:32
  SPEAKER_01: And the next episode, okay, before we hit the question, I can't wait, by the way.
• 20:36
  SPEAKER_01: I'm really excited about that.
• 20:38
  SPEAKER_01: Our next episode, we're gonna start now to talk about the rocks themselves.
• 20:42
  SPEAKER_01: So we'll begin episode three with the clastic sedimentary rocks.
• 20:47
  SPEAKER_00: Okay.
• 20:48
  SPEAKER_00: Now are you ready, Chris?
• 20:49
  SPEAKER_00: Are you ready for a question?
• 20:50
  SPEAKER_00: I'm ready.
• 20:50
  SPEAKER_01: Let's go.
• 20:50
  SPEAKER_00: Okay.
• 20:51
  SPEAKER_00: All right.
• 20:51
  SPEAKER_00: This is you know, maybe a little bit easier one than last time.
• 20:54
  SPEAKER_00: What best, best being the keyword, what best describes what happens to particles as they are transported?
• 21:01
  SPEAKER_00: Okay.
• 21:01
  SPEAKER_00: You ready for your options?
• 21:03
  SPEAKER_00: Yep.
• 21:03
  SPEAKER_00: They become more angular and well sorted, they become more diverse and larger, they become sorted according to size, they become more rounded and well sorted.
• 21:15
  SPEAKER_01: Okay.
• 21:16
  SPEAKER_01: Uh you didn't go A, B, C, or D, but it was the last thing, the last answer in there, I think.
• 21:22
  SPEAKER_01: So as soon as you ask the question, go ahead and ask it again.
• 21:25
  SPEAKER_00: What best describes what happens to particles as they are transported?
• 21:30
  SPEAKER_01: I always like to think about like when you read a question, you want to try to answer it before you go and look at the choices.
• 21:38
  SPEAKER_01: Okay?
• 21:38
  SPEAKER_00: Absolutely.
• 21:39
  SPEAKER_01: That's just good test taking 101.
• 21:41
  SPEAKER_01: So my process right away when you asked the question was I'm going back in my mind.
• 21:46
  SPEAKER_01: The formation of sedimentary rocks is a four-step process.
• 21:49
  SPEAKER_01: Weathering, erosion, deposition, and lithification.
• 21:53
  SPEAKER_01: That was my thought then when I went into that.
• 21:56
  SPEAKER_01: And then your last choice that made the most sense to me.
• 21:59
  SPEAKER_01: So yeah, go back over them again a second.
• 22:01
  SPEAKER_01: What was A?
• 22:02
  SPEAKER_00: They become more angular and well sorted.
• 22:04
  SPEAKER_01: Okay.
• 22:05
  SPEAKER_01: They don't become more angular.
• 22:06
  SPEAKER_01: They become more sorted, but they don't become angular.
• 22:08
  SPEAKER_01: Yep.
• 22:08
  SPEAKER_00: Good.
• 22:09
  SPEAKER_00: They become more diverse and larger.
• 22:11
  SPEAKER_00: Uh they become less diverse, actually, and they become smaller.
• 22:15
  SPEAKER_00: And C was they become sorted according to size?
• 22:20
  SPEAKER_00: They do.
• 22:21
  SPEAKER_00: They do get sorted.
• 22:22
  SPEAKER_00: Okay.
• 22:23
  SPEAKER_00: Yep.
• 22:23
  SPEAKER_00: And D was they become more rounded and well sorted.
• 22:27
  SPEAKER_01: Yeah, so there was nothing wrong with C, but D is a better answer because it's got more detail.
• 22:32
  SPEAKER_00: Perfect, Chris.
• 22:33
  SPEAKER_00: You're doing great, man.
• 22:34
  SPEAKER_00: Little stars all around.
• 22:35
  SPEAKER_00: Look at you.
• 22:36
  SPEAKER_00: That's great.
• 22:37
  SPEAKER_00: All right, that's a wrap on episode three.
• 22:39
  SPEAKER_00: We're starting classic rocks.
• 22:40
  SPEAKER_00: Next episode.