Earth Science Grade 11 Past Paper PDF

# WEEKLY LEARNING ACTIVITY SHEETS Earth Science Grade 11, Quarter 2, Week 2A ## VOLCANISM ABOVE AND UNDERGROUND **Learning Competency**: Describe what happens after magma is formed (MELC S11ES-llc-25) **Time allotment**: 2 Days ### Specific Objectives: - Contrast a quiet eruption with an explosive...

# WEEKLY LEARNING ACTIVITY SHEETS Earth Science Grade 11, Quarter 2, Week 2A ## VOLCANISM ABOVE AND UNDERGROUND **Learning Competency**: Describe what happens after magma is formed (MELC S11ES-llc-25) **Time allotment**: 2 Days ### Specific Objectives: - Contrast a quiet eruption with an explosive eruption - Identify several volcanic structures - Determine the major types of intrusions ### Key Concepts: - The rock materials deep within the earth's crust is in molten state, and under great pressure from the weight above it. Throughout the earthquake belts there occur openings in a surface layers through which this melted rock is forced to the surface, forming a volcano. - The movement of hot, liquid rock below and above the crust is called volcanism. - A volcano is both the opening in the earth's surface through which material erupt and the mountain built up by these materials. Magma, hot gases, and rock erupt from volcanoes. Quiet eruptions form shield volcanoes; explosive eruptions form cinder cone volcanoes. Periods of quiet and explosive eruptions form composite volcanoes. - Intrusions are underground flows of magma that cool and harden into rock without ever having reached the surface. - The major types of intrusions are dikes, sills, laccoliths, batholiths, and stock. - If you could travel down a volcano, you would eventually reach a magma chamber. - Heated magma rises up from magma chamber through cracks in solid rocks and it forces the cracks to widen. - In time magma breaks through the surface and erupts. - Vent is the central opening of a volcano. - Crater is cup-like depression that surrounds the vent. Atop some volcanoes is a large kind of crater called a caldera. ### Volcanic Eruptions: - There are two basic kinds of eruptions: quiet and explosive. - Quiet eruption is when liquid lava flows out of a volcano's vent. Thin, watery basaltic lava tends to flow quietly out of the vent. - Explosive eruption is when lava is violently blown out of the volcano. Thick, pasty granitic lava containing much dissolved gas tends to erupt violently. ### Volcanic Structures: - Two factors which determine the shape a volcano: the type of eruption and the type of material erupted. ### Major Types of Intrusions: - **Sills** forms when magma intrudes between the rock layers, forming a horizontal or gently dipping sheet of igneous rock. - **Dikes** form as magma pushes up towards the surface through cracks in the rock. Dikes are vertical or steeply-dipping sheets of igneous rock. - **Batholiths** are large, deep-seated intrusions (sometimes called Plutons) that form as thick, viscous magma which slowly make its way toward the surface, but seldom gets there. - **Laccolith** is a sheet-like intrusion that has been injected within or between layers of sedimentary rock. The pressure of the magma is high enough that the overlying strata are forced upward and folded, giving the laccolith a dome or mushroom-like form with a generally planar base. ## References for Learners: - Danielson, E.W. & Denecker,Jr..Earth Science. 2008.New York. Macmillan Publishing Company. pp.340 - 352 - Murray, Andrew V. High School Subjects for Self Study. 2010 Edition.Vol.II.2.Success Unlimited Enterprises.Quezon City. **Author: Lalane P. Arcena** **School/Station:Burgos National High School** **Division:Siargao** **email address:[email protected]**