hello let's hope you are keeping well today we will be looking at the morphology again and we're looking at the section on River rejuvenation okay I know some of you seem to find this very difficult section seems to be a bit abstract but we try to make it simple as possible for today so let's get going okay of course we will have to look at the exam guideline and what it has to cover and very clearly we see the concept of River rejuvenation okay it's not coming my highlighter so the concept of rivarly germination the reasons for juvenile rejuvenation and the features that obviously result from rejuvenation we'll also look at a bit of a past paper a question which is always important as I always say no no I'm sounding like a bit of concede II every time I mentioned that must do a question from a past paper so we're going to look at midpoints terraces fatty in a very and in size and entrenched in the end this or intense save me okay so lets us go forward now rejuvenation let's look at getting it in terms of a visual of what is rejuvenation now we look here there's a waterfall and we've already learned that for a waterfall will happen there must be a change in the grade order of a slope so here is from general to sunny quite a steeper slope so what happens the water flows down at a much faster speed okay it flows at a much faster speed having more arrows of power and therefore allowing it to have more vertical or downward erosion now here we look at the same thing and I'll move my face off here right we look here there's a midpoint a change in gradient same thing here and what happens of changing gradient the river now flows faster it's more energetic right it then is able to erode more because of the slope change and therefore it results in more downward or vertical erosion okay that's river rejuvenation please no planners it's not just about the river being more energized the river can be energized but not necessary and when we don't indicate the download' erosion then we're not talking about rejuvenation okay so let's go further all right and let's look at a next slide next slide today okay I went backwards and not forward so I'm gonna do it again I do apologize for this last let's look at rejuvenation River rejuvenation okay and clearly we can see here it occurs when a river speed and in rows of power increases okay right now what happens yeah we said it can happen due to a change in gradient where the gradient gets steeper okay an important thing it results in increase in downward or vertical erosion that's rather rejuvenation as I did it visually and have explained it now okay all right and you can see what happens here the hands are ever flowing now the surface has been lifted and any surface sunny lifted the area lower down becomes steeper okay it can be various ways you've done isostatic couple of etc in britain so uplifted what happens is the energy grows and the river is able to erode vertically can you see it's making it deeper deeper when the surface has been uplifted over erodes it's been rejuvenated speed it becomes deeper okay just showing you some characteristics or the characteristics include water flows rapidly okay with sloping sides that create steep cuts because now there's a slope is a bend it's been lifted so that gradient becomes steeper okay deep cuts oh as we also call it incisions on the valley floor okay well show you again one more time you can see the deeper cuts here from there to here when rejuvenation has occurred it happens like that all right let's go on let's look at reasons for why rejuvenation this happens lets us talk about just water that's all we think most of the time okay when the sea level is lowered all right all of a sudden you've got something like this some you use my hands okay and suddenly the sea level and I made this of a big up okay so you can see me nice I got my hands yeah they're surface now the sea level gets lowered what happens to the gradient okay it's a steeper gradient downwards water flows alright let's look at another one here when the land gets up lifted okay due to tectonic forces you did the theory of isostasy etcetera and it uplifts or they could be folding or rock it has my surface here alright and suddenly the land gets uplifted what happens there's a steep gradient water flows faster over that can you see down here and it gets uplifted okay so that's another one and the next one here we look at move my face around the volume of water of course the greater the volume okay due to increasing rainfall etc the speed may increase and therefore it can erode more downward downward alright Society in rejuvenation okay and of course another capture where wonderful captures the water of another river and when it captures the water of another river it would have a greater volume okay a greater volume therefore the speed will increase so these are the reasons for why we have the river capture let me make my face I'm not so important it does let me make my face a bit smaller alright so when we do that we learn that these are the reasons for dramatic rejuvenation okay let's look them at the features now that may for the first one we look at is a knee point right a point where the gradient changes you can see it here let us let me see it and you see there there's some change in the gradient okay that's your neat points and the one thing you know already it was a larger who could get waterfalls forming smaller could get Rapids so there's no also create other features that form here okay so let's go on I'm showing you here also any point can you see at that point the gradient changes it's a neat point all right you all got that so let's look at our full explanation of a new point and it points part of a river of course another channel where there's a sharp change in the channel slope to make the word easier sharp change in the gradient alright and this results in an increase in downward erosion right cheek to the rejuvenation so sunny does a sharp change in gradient speed increases and of course this move down would erode or vertical erosion and therefore you have your rejuvenation that's one feature let me talk about river terraces okay now look at what happens here there is the original level right there River starts to cut into this and let me use my pointer here alright the river starts to cut when it's energized down as it cuts okay it also there's a certain amount of lateral erosion which widens the very alright then when the river is rejuvinated again it's gonna cut further and it's gonna reach this point all right of course it's smaller whenever you d go home as you deep you will get some lateral movement and the top the whole be wider as you go down narrower and narrower and narrower okay same ah so the numbers rejuvenated it was wrote vertically again and they create another formation like a step and then of course and be their position etc okay and then be laterally when they're overly juveniles again it's gonna be vertically again creating another slope can you see them and these slopes are steps they create like steps on either side okay on either side those are no it's your rubber terraces at that formed due to rejuvenation remember if the Riverton rejuvenate like that you would not have these terraces for me they form in pairs on either side all right and sometimes the same height they known as Perry okay play read some additional information for you okay let's look at the picture here can you see the terraces formed can you see the terraces along the river okay this is a picture of a terrace for me okay so let's go and look at the explanation now alright we say whenever overflowing the valley floor all right experiences rejuvenation it cuts into the valley floor and of course this process continues and it creates steps at different levels we going deeper and deeper and they known as terraces and we know they can be formed or they pass my apologies we all need these little mistakes okay so they are found on both sides of the river valley as you seen in the pictures that I showed you okay let's look at entrenched or incised meanders so again you see a sketch like this where at one point there's upliftment all right and when the land has been uplifted the steep gradient forms again as I showed you all right so the river is rejuvinated it starts cutting deeper okay what happens to this meander because of that because of rejuvenation is more vertical erosion and therefore it's more in size that's deeper in to the belly all right creating an incised also known as a entrenched Vienna can you see it on the sketch it's deeper compared to this in size means cutting further down making it deeper okay so let's look at the next one this is a beautiful sketch or picture Rama alright I wish I could sketch showing this all right where can you see it's deep look at the original levels the original levels of this meander now how deep it is yeah very deep okay it's an incised me and which is a bend in the rubber all right so let's go on so inside the church may be under occurs when meandering river I keep moving my face are not doing that okay when a meandering River meandering river experiences rejuvenation resulting in more downward over this causes deep incisions you can use the word cuts resulting in size or entrenched meanders deeper the endless okay you can see all these things are clearly caused by rejuvenation then Valley in the valley I know many of you requested this because there's nothing matching many of the books etc okay I knew you were worried about this okay it's some process where terraces are created after rejuvenation okay so what has happened yet the surface can you see the change in the gradient there let me get my little pen again laser point again you see a change in the gradient day okay so it cuts down okay it cuts further in creating sort of little very shape there which is now a valley in a valley which is a smaller valley in the larger valley remember as it reads you of an edge will be vertical but there's also latter erosion which makes a value wider and when there's more vertical it cuts down into the valley creating a valley in a valley okay then we can see it here also as rejuvenation occurs naturally rosin here okay and then vertical erosion D going cutting further down creating a valley in a very okay you've got that learners I hope so so what would be a valley in a valley game highlighter newly formed terraced began uniform Terrace begins to cut back to form the valley you know first its cutting then of course it widens okay through naturally rose so because cut back backwards and take it further you can actually rosin making very widen of course this process will continues and if rejuvenation occurs okay doesn't have to cut Peter but it occurs the new terror cells will form as well due to the increasing vertical erosion as I told you tennis will form another step or form then this creates a smaller Valley okay well then that then so we have another Valley all right I'll show it to you again can you see it widens and if it's a game rejuvenation occurs then we have a valley in a valley it doesn't have to be a repeat all right we can doesn't have to be repeated all the time but of course rejuvenation occurs we are particularly rolling and we have value in the money okay now identifying features when you look at it and again identifying rejuvenation okay on a topographic map on auto photo we can look at this I mean waterfalls is clearly indicated on a topographic map we would be able to see oxbow lakes all right if this is not as clear but if it's in evident on any picture of any man or any auto photo in size meanders which you can see some time a lot of photos is deep one of our terraces as soon as you see the sometime question comes up is rejuvenation of a rejuvenation happen all right and if you identify any of these things the answer is yes rejuvenation is happening because there's a water force in the area or there oxbow lakes etc all right that's how you would answer first and I mean no more just say identify the feature which shows that there is a there was a change in gradient if it was a waterfall or the speed of the water increased therefore cater oxbow lake all right things like that all right so that's identifying your features of course we must do a question on this all right let's look at again and once again the examiner gives you a clue first thing since River rejuvenation all right tells you what the diagram is about I think we did a similar one before the same so here's your meandering River let's look at what it saying be handling River okay so we see meandering yeah all right this was before he to Venetian a now let's see what else the examiner gives us he says after rejuvenation let's see buddy whoa we getting quite deep in size beyond the sea I can you see it all right it's deep so he jus Venetian has occurred it's good anything else whoa he says up Luffman so we know some tectonic forces but it's floating with its isostatic uplift or whatever that has caused the land surface to be price therefore causing a steeper gradient and allowing for the speed of the water to increase cause rejuvenation causing more in size change the endless so can you see Glennis just by knowing and knowing how to apply my information and worked out so much about this resource so let's go on that's for the questions what type of erosion is associated you know my capture thus you will nail now a vertical and of course we say except affluent all right we know it has to erode vertically that's in our definition increasing speed row so power eroding vertically up downward let's look at the next question what evidence indicates that leverage of an let's take a place already in your sketch there's two things that were shown there one was the upliftment and you could see that clear entrenched or incised meanders clearly shown on the sketch can you see a profit and incised or trench meanders can you see how much information you can get from the source itself a very important then identify the force of upliftment all right can you see they do we can prop generally because up love me - as a stylist isostatic uplift all right it's for stop you've done this in your 810 or tectonic forces a compression and whatever causing suffices to be uplifted folding etc all right our plates meet all right and they push together forcing things up you've done this in the rating of course your teachers will discuss this when they do another capture also okay why is reeju buys the rejuvenator land not please no selective reading use your highlighter suitable for human activity not saying they can't do it why is it not suitable and immediately what should come to mind what happens when an area is rejuvinated okay the land becomes steeper isn't it the speed of the water increases right so do you talk about the speed of the water is that the main thing yeah let's get back to the question he talks about it we do fanatic land I know it's a bit vague this rejuvinated land all right it should be uplifted land okay but we forgive the question we could stop answer it all right so we would look at land becoming steeper when to eat Yuva nation occurs okay that's what the question was trying to tell you okay the land gets adjusted when rejuvenation occurs is why is it not suitable so we know it's deeper and there we go we just answer steeper slopes unsuitable isn't it for building anything deeper gorgeous farming impossible all right but I wouldn't say impossible to the memik memo gave us that but it's very difficult right in deeper goddess burning infrastructure with steep gradient is expensive can you see the answers more specialized farming and shimmery is needed so it's expensive water will not be easily accessible for human usage ok at that point because we may create some power but what is from fast all right to assess the water maybe we may have some difficulties right narrow floodplains because now this incised meanders and then the side of the inside meanders there's not much of floodplain all right reduce fertile farming land can you see it brought it up at heavy area but the simple answers that you've done already that can get you young for my heart's right then let's go to 1.0 165 in a paragraph again and I always tell you about this approximately 6/8 lines all right it's approximate explain ah important words that explain how now what how does rejuvenation could change flooville features downstream of the point of rejuvenation so there's various things how can rejuvenation do this we don't just say what happened but how it happened that rejuvenation change features now we know through your features meanders Oxbow legs whatever you can feel it features already okay and where is downstream not upstream for there's some specifics in this question that we have to highlight and note that below okay now immediately now mind what's playing in our mind okay it's below the rejuvenation what happens when the rejuvenation happens the speed of the water increases all right so what is moving faster this more loss of power all those things happen okay right so let's look at this answers now midpoint will develop between old a new point of erosion because the gradient has changed and once I change gradient happens that is actually a midpoint all right and what happens in the midpoint Waterfalls develop okay so now we have a water for developing that's a change all right vertical erosion could result in terraces okay because now our tennis forms okay it's maybe not a change but he's changing the landscape all right not totally trees not changing the flow of your feature but it's changing the landscape but the example is has given that as an answer okay so it's a bet all right a valley was enough valley so it showed in this first part it's showing how the valley has changed there wasn't there's a new valley floor alright so there's a valley within the valley alright that is formed as you see because erosion has occurred meanders around deeply Road to form in size to be endless okay and of course flat plains are road because the erosion is happening vertically so we don't have to slowly flat place we have now deeper the meanders and the number amount of space on the floodplain becomes yes alright then here it says higher velocity remove some braided streams okay this looks more like the change of the few of your features am i right learners yeah it is more but this has been accepted can you see high velocity breakthrough Levy's so I like these answers here okay because it tells us how high velocity may wash existing deltas okay high velocity will result in more oxbow lakes alright I think this really brings out the change in the fuel features but when question gives it back we sort of the wave flooville features and this was the answers okay so just remember these may be it alright but sometimes it doesn't hurt if you don't get formed these to add these ones on remember when they ask for four facts you can think of three go to the next situation make sure you put four okay so in here also we may find a valley changes to a valley in the valley all right a meander changes to in sized meander alright I'm just trying to sift through here flat plains are narrow so these are all acceptable answers also wherever the feature existed and now to be adjusted okay I hope this will make it clearer for you in when you answer in your papers all right all the best learners you keep well