1. EAST AFRICAN RIFT VALLEY:

2. STUDY MAIN MAP RIFT VALLEY  1-How many plates can you find here ? (1,2,3,4?)  2-What is the result of these tectonic plate movements?  3-What do the dotted lines stand for?  In this area: we see different fault lines (graben or “slenken’ or rifts), it’s a system of ongoing branches. In the long run one of these branches/rifts/ fault lines wil evolve into an ocean (the other fault lines will stop being active). So out of one fault line will develop an ocean because the African Plate will be split and parts will diverge (move away) from each other.

3. EAST AFRICAN RIFT VALLEY ; 6400 KM L GRABEN (SLENK)

4.  RIFT VALLEY (GRABEN, BASIN (SLENK) DIVERGING PLATE BORDERS (NEW OCEAN

6.  At the border of the Republic of Congo you can see a series of lakes (and next to it also Lake Victoria).  See ; Google “Rift Valley”(East African Rift System EARS ) = long system of graben, valleys, basins (slenken) from Syria till Mozambique: total length 6400 km, width 30-100 km and depth 100s till 1000s of metres (including fault line which runs through the Red Sea and Gulf of Aden  What is the story behind? Theory of Wegener (plate tectonics) developed in the 60’s: the crust (lithoshere) is divided in different plates which drift on the mantle (asthenosphere); empowered by the convection currents old theory: continents drift over the oceans (Morgan);  In the EARS a convection currents heats the crust which becomes brittle and cracks/faults appear and certain parts sink : result is g…., the Rift Valley  In this area: we see different fault lines (or rifts or graben (Dutch “slenken’). It’s a system of ongoing branches. In the long run out of one of these branches/rifts/ fault lines an ocean will evolve (just like the Red Sea). So the African Plate will be split in two parts which will diverge (move away) from each other (first we see valleys with lakeslater an ocean) RIFT VALLEY

7. G59Three kinds of endogenic effects on differences in altitude of the earths’s surface  1Horst=  2Graben=  3Fold= On a fault, pieces of crust can move either h…….. or v…………. Another name for fault = cr…… G60  Plates =  Main movements (3)of plates =  Mid Atlantic Ridge =  At plate boundaries you find v………….. and e………….. G 59 FOLDS, HORSTS AND GRABENS G60 PLATES AND FAULTS

8. Two types of diverging plates:  Mid oceanic ridges or  Intercontinental rifts (faults, graben, slenk):  Magma from the mantle (asthenosphere) pours out, solidifies and builds new crust (lithoshpere) which moves away in both directions from the volcanic plume  Africa splits in the Nubian Plate and the Somalian Plate and a new ocean will develop DIVERGING PLATE BORDERS (MOVE AWAY FROM EACH OTHER)