waterfalls and gorges as part of the edexcel GCSE 91 geography course right okay so the key words you're gonna have to have for this on waterfall hardrock okay which for the named example its Winstone soft rock which also for the named example is limestone erosion which in this case is hydraulic action abrasion and solution plunge pool overhang unsupported rock fall treat and Gorge okay and there's always when you get to the end of the video you can come back to the keywords page you can say there's a kick off to write your own answer alright it's a hissy first diagram hard rock soft rock remember for you diagram always use a pencil okay and don't use a ruler okay cuz then real life it wouldn't be straight okay so do it freehand right so the key points waterfalls occur in course of the river okay and they have two layers of rock hard rock on top and soft rock on bottom okay so that's very obvious from this picture okay from this diagram we've got my hard rock on the top and the soft rock on the bottom okay here's your second diagram they're gonna be jewelry okay always remember to annotate it okay see I've got the annotations here okay you might want to put some more in just to be sure okay key points for this diagram the soft rock isn't really the way much easier than the hard rock through solution hydraulic action and abrasion okay the sediment is washed away downstream by the river creating a plunge pool so this here is the punished core okay so the water's come down its eroded this soft rock okay and all the sediment from here has been taken away so it's just left this plunge pool here okay here the water debris and rock is swirled around allowing the plunge board to be made bigger so say if you do have some debris in here okay hydraulic action from the water coming down the abrasion from the debris hitting the walls okay in this solution it's a softer Rock and save it's limestone that's going to be eroded away by solution and that's going to make it bigger okay here is the third diagram okay so ask the plunge pool becomes larger the overhang becomes less supported okay so this peak here is the overhang if you look back here and I tasted it here so you can see the overhang okay so that's become larger okay and then one thing overhang is unsupported okay Rock fall occurs which is a type of mass movement okay so the rock fall gonna occur it and that's gonna mean that that overhang is falling down okay and the Hard Rock collapse is making the waterfall retreat upstream okay so basically what you've got here is what looks like the first drag on again okay it's gone back it's like a cycle mix okay see as I said in retreat upstream okay the cycle begin again I begins again with the area where the rock walls fall was becoming the gorge so this is the gorge here between the valleys where the waterfall was okay that becomes what the gorges okay the Hard Rock which is quite just will be eroded down and carried downstream and larger particles so you have it here it's been eroded gonna be taken downstream often you'll find larger bits of rock downstream as it's not got the force the hydraulic action of the waterfall coming down okay and so the cycle is going to begin again so the named example of this is high force on the river tees okay just in teasdale County Durham with hard rock being Winston which you can see here it's the lighter color and the soft rock being limestone which is at the bottom so that's going to be eroded away by solution okay an important part of this exam is applying their knowledge so they might give you a diagram like this Oh picture like this and you're gonna have to list some points off about it it's gonna always stay you can see the soft rock the hard or rock you can see where the main waterfall is okay this picture is obviously taken at a time of high rainfall this is another second waterfall occurring here as you can see there's a lot of water coming over the waterfall at the period of time and if you look down here you can see the larger rock which will have been the overhang will just come off okay that's that there okay so it's a very good diagram to see and practice annotating