Mountain Building, Volcanoes, and Earthquakes

Bellwork – 3-17 What theory is the cartoon at right making fun of? Name the type of plate boundary and what may form there: A B What is a subduction zone? What kind of boundary do they form at. What is the theory of sea floor spreading What is the theory of plate tectonics? What causes the plates to move

Notes Exit Quiz – answer on an index card Why wasn’t the theory of continental drift widely accepted? What theory says that the lithosphere is divided into 7 plates that are moving? What is a plate boundary? What forms at subduction zones? Draw a transverse boundary and describe what might form there What do scientists call the area around the pacific ocean with a lot of volcanic and seismic activity?

EQ: How do mountains form? SC.7.E.6.5 & 6.7 Describe what forces cause mountain building, and how it is related to plate tectonics.

How can plate tectonic motion cause deformation? Plate movement causes stress on rock structures. Deformation – when a rock changes shape due to stress. – (great pressure and heat) It causes rock layers to Bend or Break under stress Rocks all start out as layers deposited on top of each other over time. Bending Breaking forms folds Forms faults

What are 2 kinds of folds? Anticlines Synclines

1. Synclines Youngest layers are found at the core of a fold (center) older layers are on the outside of the fold Appear arched inward like a bowl Youngest rocks oldest rocks

2. Anticlines The oldest layers are found at core (middle) Youngest layers are found on the outside of the fold Look arched upward they are high in the middle oldest rocks Youngest rocks

Where are the synclines and anticlines?

What are faults? Fault –forms when large blocks of rock break and move past each other Fault plane – where the 2 fault blocks meet Footwall – the block under the fault plane Hanging wall – the block above the fault plane

What are the types of Mountains? The movement of material and heat in Earth’s interior moves the plates that cause Mountain Building The plates are always in motion so mts are always forming. They can form through folding, volcanoes, faulting, and uplifting (when the land rises or mountains form) https://www.youtube.com/watch?v=W8Cr_pplBIo

Name the kind of plate movement and the mountains formed

What are the 3 types of mountains? Type of mt Folded Volcanic Fault block How formed Type of boundary they form at Picture example

When you are done: complete the mountains notes sheet and Mountain illustrations – p. 185 Folded Mountains Fault Block Mountains Uplifted mountains Volcanic mountains

Volcanoes

– T/F Lava is inside earths crust and may contain trapped gases Volcanoes can form at divergent plate boundaries A subduction zone is formed at transform boundaries Dormant volcanoes will never erupt Volcanoes can only form at plate boundaries

Volcanoes EQ: How do volcanoes change the Earth’s Surface? Describe formation of volcanoes, eruptions, and how they change the earth’s surface.

What is a volcano? Volcano: any place where gas, ash, or melted rock come out of the ground. Can be a mountain or a crack in the ground Can be on land or under water

What is a volcano? Volcanoes form as rock below the surface melts and becomes magma The warm magma rises to surface and becomes lava. Lava and clouds of gas (ash clouds) erupt from an opening called a vent

Label the parts of the volcano Magma, lava, vent, ash cloud

What are kinds of volcanic formations Fissures and lava plateaus – when lava flows from cracks in the earth’s surface forming a solid layer

Crater – an opening or depression at the top of a volcano caused by eruptions

Caldera – When the magma chamber empties below a volcano and it collapses leaving a basin shaped depression

Where do volcanoes form

Volcanoes at divergent boundaries Plates move away from each other Create fissure eruptions and shield volcanoes Ex/ mid ocean ridge and rift valleys

Volcanoes at convergent boundaries Plates move toward each other at subduction zones Form composite volcanoes and calderas as magma rises and erupts Cascade Mt Range (west coast of US)

Volcanoes at Hot Spots They happen in the middle of a plate when a mantle plume rises to the lithosphere Forms chains of volcanic mountains Hawaiian islands

Volcanic mountains – classified based on shape and eruption style

Shield Volcano Mauna Kea volcano gentle slopes non explosive slow flowing lava eruptions many times larger than a composite or cinder cone volcano. Mauna Kea volcano picture from www.usgs.gov

Cinder Cone - Paracútin Steep sided, small volcano Form from Explosive eruptions – lava contains pyroclastic materials – cinders and bits of rock. On February 20, 1943, a Mexican farmer noticed that a hole in his cornfield that had been there for as long as he could remember was giving off smoke. Throughout the night, hot glowing cinders were thrown high into the air. In just a few days, a cinder cone several hundred meters high covered his cornfield.

Composite Volcano – Mount St. Helens Large volcano with steep sides Alternating mild eruptions and explosive eruptions alternating layers of lava and hot ash and bits of rock Erupted in 1980 57 fatalities Over 7000 big game animals perished 4 billion board feet of timber (enough to build about 300,000 two-bedroom homes) destroyed Destroyed 27 bridges, nearly 200 homes. Blast and lahars destroyed more than 185 miles of highways and roads and 15 miles of railways.

Turn and talk What kind of damage and environmental changes might have been caused by the eruption of Mt. St. Helens. http://www.youtube.com/watch?v=-H_HZVY1tT4

57 fatalities Over 7000 big game animals perished 4 billion board feet of timber (enough to build about 300,000 two-bedroom homes) destroyed Destroyed 27 bridges, nearly 200 homes. Blast and lahars destroyed more than 185 miles of highways and roads and 15 miles of railways.

Where do volcanoes form? Volcanoes can form at Plate Boundaries or in the middle of a tectonic plate Ring of Fire: an area in the pacific ocean with a lot of volcanic activity and earthquakes.

Exit: t/f The of volcano shown is a shield volcano Volcanoes can only form on plate boundaries Hot spots are located on tectonic plate boundaries. Cinder cone volcanoes are the largest All volcanoes form mountains

Summary Questions What kind of volcano is shown in the picture below? Which kind of volcano might have alternating violent and non violent eruptions What is a hot spot volcano? How is it different from other volcanoes? What volcanic landform might form at divergent plate boundaries What volcanic landform forms at hot spots What volcanic landform forms at convergent plate boundaries?