00:00 (upbeat music)

00:02 Good day, students.

00:12 My name is Mr. Nkanu, your geography teacher.

00:18 Today, we are looking at earth internal processes.

00:24 In particular, we are considering

00:27 karst to pro-graphy

00:29 by casts to pro-graphy within line stone regions.

00:35 At the end of the class,

00:38 students should be able to define casts region

00:42 to identify the characteristics of cast region,

00:47 explain surface and on diagram features of cast regions,

00:52 also explain the importance of line stone.

00:56 Lastly, we'll identify where line stone is found

01:01 in Nigeria.

01:04 Line stone region refers to a stretch

01:09 of land occupied by line stone.

01:15 It is very, very unique

01:18 compared to the nomad to pro-graphy you know.

01:24 Land stone is a sedimentary rock

01:28 of organic materials made up of calcium carbonate.

01:33 They are derived from accumulation of purers

01:39 and shells.

01:41 If you get to the sea, the sea site,

01:45 you're good to see shells

01:46 or the mamas that died, their bones and everything.

01:50 That is where we get this.

01:52 And then when magnesium is present,

01:56 it is termed billumite.

02:00 Chalk is very pure form of line stone,

02:03 white and rather soft.

02:07 Now, let's have an idea

02:11 of the characteristics of this region.

02:16 How does it look like?

02:20 The first time when you get to this region,

02:23 you will discover that it is soluble.

02:26 Why?

02:27 Line stone in a soluble box is made up of soluble

02:33 by the action of rainwater.

02:34 The rain moisture brings a weak acid

02:39 from the atmosphere.

02:41 And when this water drops on the line stone,

02:46 it dissolves it and makes its weak and is soluble.

02:51 So that's one of the carrots that we are going to find out.

02:56 Number two, if you get to any line stone region,

03:01 the vegetation is not luxuriant.

03:06 It is not evergreen.

03:08 It is not very fresh.

03:10 Now, in a certain sense,

03:12 you will not get a thick vegetation cover

03:15 on line stone region.

03:17 The total color term, when you get to a line stone region,

03:24 you will not see a surface drainage,

03:27 like you see on river Naja, river Bainway,

03:30 in your dust stream.

03:31 You are going to see short distance.

03:34 You see a stream here and that stream will disappear

03:38 because of the openings that is in that particular

03:42 topography and the reason is that the water

03:46 is able to penetrate.

03:47 That means the land is permeable.

03:51 That's why you will not see a full flown river

03:54 or stream on it.

03:55 You see short, after a while to disappear,

03:58 then it will come out at the other side.

04:01 What's the next character?

04:04 The next character or feature that can be found

04:08 on a line stone topography,

04:11 we are going to see joints and rugged.

04:14 That is joint.

04:16 Like I was trying to explain,

04:18 if you look at that interlocking,

04:20 you see that it's joint together.

04:22 That's what I'm going to see when you get to a line stone

04:26 to pro-graphy.

04:27 And this is because this is where it at the bones,

04:30 what forms of corals, the bones of the animals,

04:32 late.

04:33 That's why you see all those joints.

04:36 Then also when you get to a cast region,

04:41 the cast region and the line stone region is the same thing.

04:45 So when I say cast region, I also mean the line stone region.

04:50 So you're going to meet a dry surface to why.

04:54 When you get to that place, you're not

04:55 going to see pools of water.

04:58 Because the rocks are joints.

05:00 Once it rains, because of this joint,

05:03 the water easily goes down.

05:05 And the valley is usually dry.

05:09 And sometimes water, or between the hard rock on the ground,

05:13 may re-image below the line stone as a spring.

05:21 The next feature we have is a presence of depression.

05:26 The line stone region will not be like your mammal,

05:30 like I said, tires, or your house, whatsoever.

05:32 We are going to meet depression.

05:34 Line stone regions contain depressions of very sizes and depths.

05:41 And at this time, we want to just look at some of the features.

05:50 And the first feature I have is what we call the cracks.

05:53 Please do not allow the name to disturb you.

05:55 It is just like somebody discovering something

05:58 and then naming that thing after your name or the local language.

06:03 So we call it cracks.

06:06 That is one of the features you are going

06:08 to find in a line stone region.

06:12 And it's a surface feature.

06:13 We have those surface features and on the ground feature.

06:17 We are starting with surface feature.

06:20 And if you look at the diagram I have there,

06:22 you can see it.

06:23 You can see those openings.

06:25 That is what we call cracks.

06:28 It is formed as a result of progressive wetening,

06:32 as a continuing raining.

06:34 You discover that those joints, the water that comes on,

06:37 it washes down the lines stone because it is already soluble.

06:41 So those holes keep on increasing, increasing, increasing.

06:45 And we call them cracks.

06:48 And after a while, they become so enlarged.

06:52 You are going to meet another kind of feature

06:55 that we call clings.

06:57 And clings are surface features of isolated

07:01 and rectangular blocks that are in rectangle or squares

07:06 between the joints or the cracks.

07:09 You are going to see it.

07:11 And it is formed as a result of progressive wetting

07:15 of cracks of joints by solution from line stone pavements.

07:20 Such enlargements of pavements or joints,

07:25 already I recall that cracks.

07:27 Then we go to this, the clings.

07:31 In the clings, there are surface features of isolated

07:34 and rectangular blocks which exist between the joints

07:40 of the topography.

07:43 Another feature you will find on a line stone region

07:49 is what we call swallowholes or sinkholes.

07:53 It is called a swallowholes or sinkholes.

07:56 What are sinkholes?

07:57 These are surface features.

08:00 They are small depressions carved out by solution,

08:04 wearing water, sinks into a line stone

08:07 at the point of weakness.

08:10 When there is a weakness, you discover that the water will sink.

08:14 These must-more openings are called sinkholes.

08:19 We have Dolan.

08:21 Dolan, this is formed when a number of several swallowholes

08:28 are joined together.

08:29 Deformed in larger depression, we call that Dolan.

08:35 Then we have uvala.

08:38 These results when several Dolans join together

08:44 to form deeper depressions.

08:48 You are going to meet all these as you get to the lines

08:51 to the region.

08:51 The next feature I have is called pojis.

08:55 These are formed from larger depressions.

08:58 We have smaller depressions.

09:00 Here we have larger depressions.

09:02 Look at what I have by the side as a picture.

09:04 You can see the picture, the opening is very wide due

09:10 to 14 due to cracks.

09:15 Now, what we've looked at before is what we're

09:18 going to see on the surface.

09:20 But what about the opportunity to enter under?

09:24 Are there other features?

09:25 Sure, we're going to look at these features.

09:28 And the first we're looking at is on the ground features,

09:31 what we refer to as caves and caravans.

09:35 These are on the ground features of Lans Tun region.

09:39 They are large on the ground spaces,

09:43 formed as a result of sinking and flow of water

09:48 into the Lans Tun through the joints and bedding plains.

09:54 Look at the picture I have here.

09:56 You can see an example of a cave.

09:59 When look at the one on top, these are the joints.

10:03 As it keeps already, what are in touch

10:05 to this joint into the Lans Tun region

10:11 and from this cave as a whole opening?

10:14 Though you're going to see a stalactite,

10:16 I'll talk about that shortly.

10:18 We meet Pila when we stalactite and stalactmage

10:21 to whether we call it Pila and then we have on the ground river.

10:25 It's a spectacular topography.

10:28 So besides these caves, we have another on the ground

10:33 kind of feature we call Lans Tun Gorge.

10:39 These are the vertical sides formed when the roof

10:42 of an underground cave collapses.

10:45 Or if accords across and run down into the Lans Tun region,

10:52 we have resurgence or springs.

10:55 I remember I mentioned to you as when I was starting that,

11:00 when you get to this particular region,

11:03 at the top, it will be dry.

11:06 You'll notice springs that go up the openings.

11:09 But where is this water?

11:11 When it sinks into the ground because of that opening,

11:15 it gives rise to springs in the ground.

11:18 This results from water sinking into the on the ground.

11:21 When the water meets hard rock of on the ground,

11:23 we call it an impermeable rock.

11:25 It cannot go beyond there.

11:26 So it settles there and becomes a spring.

11:29 It's really a mage later, either because of erosion

11:33 and you see a spring coming out.

11:36 We have stalactites.

11:39 I mentioned stalactites.

11:41 You could see in the picture I have there,

11:45 these are found in caves.

11:48 That's a sample of a cave.

11:50 You can see some slender things.

11:52 Growing up downwards.

11:55 Growing up downwards.

11:57 And later on, the one going from ground

12:01 is called stalagmites.

12:03 If the stalactites from up and the stalagmites from down,

12:08 join together, we're going to have a pillar.

12:13 There are sharp slender and downward-growing pinnacles

12:16 that hang from the roof of the cave.

12:19 They hang, they are called stalactites.

12:22 This is stalagmites, which now grows from under the cave.

12:27 These are also the ground features limestone region.

12:30 They are formed when water drifts down the stalactite

12:33 to the floor.

12:34 If a question then, of course, why calcium is deposited

12:38 leading to the formation of stalagmites?

12:42 St stalagmites are shorter, fatter, and more rounded.

12:47 Look at the diagrams I have there.

12:49 You could see it growing from under.

12:51 Look at the stalactite, very thin.

12:54 But stalagmites are quite, you know, fatter and they are shorter.

12:59 So when stalactites and stalagmites

13:04 join together, you're going to have what we call a pillar.

13:09 And the pillar is next on the ground feature,

13:11 want to look at, it's a natural pillar.

13:14 It's formed by the joining of stalagmites hanging

13:18 from the roof of the cave.

13:21 And they stalagmite growing from the floor of the cave.

13:25 St stalactite coming down, stalagmite growing, then they join.

13:29 Then you're going to have the limestone pillar.

13:33 Now, we've looked at the underground features

13:40 and the features that are on top.

13:43 That is an outward features.

13:46 But what we studied in this, why are we going into all this?

13:51 You must know and not clearly and very well

13:55 that limestone is so important.

13:58 So next up, we'll be looking at the importance of cast regions.

14:04 Importance of cast regions.

14:06 Why cast region be studied?

14:10 And the one is that limestone regions provide limestone,

14:16 which is an essential raw material, which is often used in building.

14:23 And it is cooperate for cement industry.

14:27 The raw material for cement that is used to build your house

14:32 and where you are is gotten from limestone.

14:35 So we have to move something about that region.

14:38 Number two, in Nigeria, you will discover that we are blessed.

14:45 We limestone.

14:46 We have it in the wake of August 8th here.

14:49 We have it as a dam.

14:51 Still August 8th here.

14:52 We have it at in Calago.

14:54 We have it at Calaba Cross River.

14:57 We have it at Sopoto.

14:58 And all this limestone are used for both cement,

15:03 sometimes glasses and feet.

15:07 Limestone is also used for mating of iron and fin, for example,

15:12 in raw value of Western Germany.

15:16 Limestone, which is used as flocks,

15:20 is got and used in the iron and steel plants of the region.

15:26 You see how important it is.

15:29 Most limestone regions are on that ground water.

15:33 They have on that ground water, like I explained earlier.

15:37 All of them are going down.

15:39 Going down, you cannot see any level flowing on top.

15:42 When this water penetrates and gets to an impenable rock,

15:47 the water settles there.

15:48 And when you are drilling your dough hole,

15:50 when you say several, no length of iron down,

15:54 and you touch this, then you have to get that water for use.

15:59 The water will put penetrates to the base of the limestone

16:02 and meet non-polar rock may re-emage to surface

16:07 as spring or resurgence.

16:11 Do you know that it serves a story center?

16:15 We test to them out.

16:18 Do it that to shut up, to go and see the scenes for themselves.

16:21 Or we go to a raccoon room.

16:23 So you can have a fair idea of what is all about.

16:26 So it is important, as we don't go there free.

16:32 When I go there, you pay.

16:33 So it also brings money to the government.

16:37 And it's only available to learn more.

16:39 So even in some advanced countries like USA,

16:44 and then other places is a very great tourist attraction.

16:51 I've been able to bring to you some importance of limestone

16:57 region.

16:58 So on your own, you are going down to take this assignment

17:03 and practice.

17:04 You will explain the world, cast a program fee.

17:08 You will also mention five characteristics of cast regions,

17:12 like I mentioned to you earlier.

17:14 You will write short notes on dolomites, on chalk,

17:18 on resurgence and their solubility.

17:23 Thanks for watching.

17:25 My name is Kanu, and you.

17:28 [MUSIC PLAYING]