Metamorphic rocks are formed from pre-existing rocks (igneous, sedimentary, or other metamorphic rocks) that undergo changes due to intense heat, pressure, or chemical processes deep within the Earth's crust. Examples include marble (from limestone) and schist (from shale).
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00:00So students, I am going to tell you the basic definitions of sedimentary rock and igneous rock.
00:08The third one is metamorphic rock.
00:12Metamorphic rock, as you can see, the word that we have here,
00:16it means metamorphism.
00:18It means to change.
00:20To change.
00:22It means that this rock is formed due to the change of igneous and sedimentary rocks.
00:28The condition of the sedimentary rock is not the same as that of the igneous rock.
00:32Instead, a new rock has been formed.
00:33We call it metamorphic rock.
00:35Basically, either the metamorphic rock is of igneous or sedimentary rock.
00:38But its new characteristics and properties do not match with either igneous rock or sedimentary rock.
00:43That is why we call it metamorphic rock.
00:46There are two processes of metamorphic rock.
00:48One is thermal metamorphism.
00:59Thermal metamorphism.
01:01And the second one is contact metamorphism.
01:09Thermal metamorphism is the process of modifying the source of heat.
01:14Temperature.
01:15Heat.
01:16It means that the surface of the earth is being directed by a volcano.
01:20And the magma is in its way towards the surface of the earth in any specific direction.
01:26So, during the journey, when the magma crosses this area,
01:29and if there is an igneous or sedimentary rock present there,
01:31then due to its heat, the rocks on the sides burn or change their properties.
01:36So, for example, if we have a granite rock there,
01:42then magma passes near the granite rock.
01:45Due to its heat, the granite changes its properties and changes in the genesis.
01:49So, genesis is a metamorphic rock.
01:51Similarly, in the second case, contact metamorphism.
01:54In this, the pressure of the tectonic plates develops.
02:01That's why it happens that when our plate is tectonic,
02:04when it moves due to any reason,
02:06specifically, you can say that the energy stored in the plates,
02:10there is a method to release that energy.
02:12So, when it is released, the plates move.
02:14So, due to the movement, the area where the plates are lying,
02:18due to their pressure, the rocks that are already present there,
02:21or if there is an igneous or sedimentary rock present there,
02:23they change their properties.
02:25Due to intense pressure.
02:27So, due to this, a new rock is being formed.
02:29It is neither igneous nor sedimentary,
02:31but it is a metamorphic rock due to contact metamorphism.
02:33Now, if you want to take an example of this,
02:35then we have slate.
02:37Slate is a metamorphic rock,
02:39which is a clay or sandstone.
02:41Due to its metamorphism, due to the pressure of the tectonic plate,
02:45due to the pressure, the sandstone or mud clay
02:48gets converted into the slate.
02:50Is it clear, student?
02:51So, this was the contact metamorphism.
02:53So, student, we have done an overview in general
02:55about rocks and their types.
02:57So, I will brief you a little.
02:59We have defined the rock.
03:00Rock is a natural substance.
03:02It is an organic origin.
03:04It is a part of our planet.
03:06In the opposite, we have seen the mineral.
03:08We have a unique combination of chemical and physical properties.
03:12Its structure is unique.
03:14There are two or more minerals in a rock.
03:17So, the difference is also that the mineral is of rock.
03:19We have defined it.
03:20Then we talked about the types.
03:21Basically, sedimentary, igneous, and metamorphic.
03:24We have three types of rocks.
03:25We have defined those rocks separately.
03:27There are 21 types of rocks,
03:28which are formed by cooling and solidification of magma or lava.
03:32Their further types are protonic rocks,
03:34i.e., 2C rocks, 2C rocks, and hyperbosal rocks.
03:37In their example, we have basalt.
03:39Lava basalt is an important example.
03:40Similarly, the right one is obsidian.
03:42Obsidian is an igneous rock.
03:44In ancient times, obsidian was used to kill animals, to make tools.
03:51So, obsidian was used as a cutting tool.
03:55Similarly, we have granite and pumice.
03:59You must have heard about pumice.
04:01It is a rock that floats on water.
04:03It is well-known that pumice floats on water.
04:07The second type is sedimentary rock.
04:11We have defined three types of sedimentary rocks.
04:13They are mechanical-formed sedimentary rocks,
04:15chemically-formed sedimentary rocks,
04:16and organic-formed sedimentary rocks.
04:18There are many types of these rocks.
04:19We have a lot of sedimentary rocks in our surface.
04:23For example, we have china clay, muddy clay, chalk,
04:26coal, rock salt, and chypsum.
04:28We have many examples of these rocks.
04:30The third type is metamorphic rocks.
04:32We have defined metamorphic rocks to change igneous and sedimentary rocks into metamorphic rocks.
04:37We have defined metamorphic rocks to change igneous and sedimentary rocks into metamorphic rocks.
04:41There are many types of these rocks.
04:43For example, we have the genesis rock, which is in the form of granite.
04:46Similarly, we have the slate rock, which is in the form of clay.
04:53Similarly, we have the marble rock.
04:55Taj Mahal is made up of marble.
04:58Marble is also a metamorphic rock.
05:00Basically, it is made up of limestone.
05:02It is a thermal metamorphic rock.
05:04Okay students, this is our lecture about rocks and their types.
05:08Hopefully, you have understood this.
05:10If you have any questions, you can ask them.