hi students i am miss deya el mundo and today i will be discussing to you our first lesson for grade 10 science which is all about the lithosphere are you excited by the way this lesson is anchored with a division made module of sdo kalokan for grade 10 science week one entitled lithosphere the rocky skin of earth the most essential learning competency to be tackled here is describe and relate the distribution of active volcanoes earthquake epicenters and major mountain belts to plate tectonic fury with the code that you can see on the screen in this lesson we would also like to describe the earth's lithosphere and differentiate oceanic and continental crust infer that the earth's lithosphere is divided into plates [Music] identify the major lithospheric plates and determine the scientific basis for dividing the lithospheric plates so without further ado let's start our learning for the day let me show you a picture [Music] what is this correct it's a world map what can you see in a world map that's right in a world map you can see countries continents oceans islands all with different colors i'm sure that you are very much aware of the different features of a map since you have been using this in your lower grades especially in your araling palipunan subject now let's see the next map have you seen this map before what is this map all about is the world shown in the first map different from the world shown in this map [Music] now let's place them side by side as you can see both are maps of the world however the first map which you can see on the left side of the screen shows the waters that we have when i say waters i mean the seas and the oceans the map on the right on the other hand only shows all the plates in the world which includes all the land and even the land below the water and we call all this land the lithosphere let's inspect the right map further in this map we can see tectonic plates and plate boundaries the smaller sections of the lithosphere are called tectonic plates this yellow plate is one tectonic plate this brown land is also one tectonic plate and same with this small pieces they are all called tectonic plates plate boundaries on the other hand are edges that separate the tectonic plates with one another [Music] if this is one plate the pacific plate and this is the nazca plate which is another tectonic plate then the line in between them is a plate boundary as we can see in the map there are lots of plate boundaries all over the world [Music] now let's go to the different types of lithospheric plates what are the two types of lithospheric plates again [Music] correct we have the continental lithosphere and the oceanic lithosphere first let's discuss the continental lithosphere [Music] the continental lithosphere is thick and is found under land masses it has an average thickness of 25 to 70 kilometers and is composed of old rocks [Music] it has an average density of 2.7 grams per centimeter cube and majority of the rocks that make up continental lithosphere are called granite well this is how a granite looks like on the other hand for oceanic [Music] lithosphere is thinner compared to continental crust or continental lithosphere with an average thickness of 7 to 10 kilometers it is younger according to studies than continental crust and is denser with an average density of 3.0 grams per centimeter cube now if continental lithosphere is usually made up of granite rock oceanic lithosphere is usually made up of basalt or basalt rocks which looks like this [Music] here is another diagram showing the continental crust and the oceanic crust as we can see here the continental crust is much thicker compared to the oceanic rust however the oceanic rust is denser or has greater density compared to continental crust and in this diagram it can be seen that the lithosphere is made up of both the crust and the upper mantle now let's try to fill in this table comparing the different characteristics of continental lithosphere and oceanic lithosphere first the relative age which is older and which is younger [Music] correct continental lithosphere is older than oceanic lithosphere how about the relative thickness that's right continental lithosphere although it is older it is thicker than oceanic lithosphere next the relative density [Music] which is denser [Music] okay so oceanic lithosphere is denser than continental lithosphere if you remember the numbers the average density of continental lithosphere is around 2.7 grams per centimeter cube while an oceanic lithosphere will have an average of 3.0 grams per cubic centimeter finally the type of rock very good continental plates or continental lithosphere are mostly made up of granite while oceanic lithosphere is made up of basalt or basalt so now you have already learned the basic differences between continental lithosphere and oceanic lithosphere let's now move on to the different types of plates we have two types of plates we have primary plates and secondary plates now what do you think is the difference between the two okay so primary plates are called primary because they are larger than the secondary plates so that is only or basically the difference between the two the earth has seven primary plates and eight secondary plates [Music] given the map here can you name some primary plates [Music] okay so the earth's primary plates are [Music] of course the pacific plate the north american plate eurasian plate african plate antarctic plate australian plate and south american plate now what do you notice about the names of these primary plates very good most names of these primary plates are taken from the names of the continents except pacific plate however pacific plate is the plate that can be found under the pacific ocean on the other hand eurasian plate is like the combination of europe and asia which basically sits on the same tectonic plate so now let's go to the secondary plates can you name some of them as stated a while ago secondary plates are smaller than primary plates [Music] the secondary plates are juan de fuka plate can we find one the foca plate this one this small plate nazca plate [Music] coco split caribbean plate philippine plate arabian plate engine plate and scotch and plate see they are very easy to find because you can distinguish primary plates from secondary plates by their sizes now we are done with the different types of plates according to composition and then the different types of plates according to sizes let's go now to this question [Music] what is the basis of scientists for dividing lithospheric plates how did they know is there really a physical boundary between these plates how did they know that the shape of the arabian plate is like this how did they know that the philippine plate is just this one okay we know that the philippines is not with this shape because the philippine is an archipelago but then how did they come up with this divisions any wild guess [Music] to help us answer that question let's look at these pictures which can be found in your modules the first one is the map of distribution of earthquake epicenters which are shown in the darker areas so this means that these darker areas represent areas where most of the earthquakes occur of course other areas would also have earthquakes but then most of the earthquakes would happen in this dark area next we also have the map of volcanic activities now what do you notice [Music] okay so just like the map of the distribution of earthquake epicenters the second map would also show points or places where there are more volcanoes or volcanic eruptions compared to other places [Music] for example this area has more volcanic activities compared to the center of this area and we also have other volcanic activities in these places third we also have the map of the major mountain ranges in the world the third map is quite different from the first and second map because the center of the map is not the pacific ocean as you can see the pacific ocean is divided into two places instead of being in the center the pacific ocean is found on the left side and on the right side but then as you can see most of the mountain belts are found in this area and in these areas all right now can you see any similarities among the three pictures or diagrams okay i'll give you 20 seconds to think of it and if you are done please comment your answers on the chat box [Music] okay so you said that most of the highlighted areas are found in the pacific ring of fire that is correct so the one being shown in the second map is actually the pacific ring of fire okay so we can say that the three geologic events and features that are being shown in the three diagrams which are the earthquakes in the first map active volcanoes in the second map and major mountain ranges in the third map they are distributed near or along plate boundaries okay so if we compare for example the second map from the first map that you have been seeing a while ago if you will look at the boundaries of the pacific ocean or boundaries of the pacific plate it is very similar to the marks showing the active volcanoes okay also here we have the nazca plate okay you can see here that there are dots that seem to be part of a line or a boundary so therefore we can say that scientists have been using these events and features as bases for identifying the plate boundaries because of course these plate boundaries are not there in the first place okay so scientists have to gather lots of data which includes earthquake data volcanic eruption data and the present mountain ranges in order for them to plot these plate boundaries all right so any questions [Music] so if there are no more questions this would be the end of our discussion so i hope you have understood the lesson for today and if you have questions that you are just shy to ask about please don't hesitate to send me a message or post us a comment and then i'll try to answer them as soon as i see them so that's all for today goodbye and thank you for watching