1. Volcano Rocks & Landforms

2. What are the types of lava rocks?
Both are produced by quiet eruptions Aa
Is a sharp, jagged surface.
Forms from lava flows that are cooler and slower moving.
Pahoehoe
smooth, “ropey” surface
Forms during fast moving, hot lava flows

8. Other types of lava rocks
Rhyolite--Magma that is high in silica, has the same composition as granite.
Pumice-- Gas bubbles are trapped in cooling lava, leaving spaces in the rock. Also high silica content.
Obsidian-- Forms when lava cools quickly, giving it a smooth glossy surface. High silica content.
Basalt-- Magma that is low in silica flows easily and produces dark colored lava.

9. Rhyolite

10. PUMICE

11. Obsidian

12. When Lava sprays out of the ground like water from a fountain, the lava stretches and hardens into thin strands. These lava strands are called Pele’s hair.

13. LAVA Landforms

14. Calderas Large depressions in volcanoes formed by collapse
Nearly circular
Size exceeds 100 km in diameter

15. Crater Lake is a caldera that formed when Mt
Crater Lake is a caldera that formed when Mt. Mazama collapsed 7,000 years ago.

16. Crater Lake, Oregon

17. Wizard island is a small cinder cone that formed after the collapse of Mt. Mazama.

18. Wizard Island in Crater Lake

19. Lava Plateaus
Fluid basaltic lava extruded from crustal fractures called fissures.
Layers and layers of lava build up over millions of years

20. Rocks & Landforms
Made from MAGMA

21. 10.2 Intrusive Igneous Rocks & Landforms
Igneous rocks & landforms - MAGMA.
10.2 Intrusive Igneous Rocks & Landforms
Plutons are intrusive igneous structures that result from the cooling and hardening of magma beneath the surface of Earth.
• classified by their shape, size, and relationship to the surrounding rock layers.
this include necks, dikes, sills and batholiths

22. Volcanic Necks Forms when magma hardens in a volcano’s pipe.
The volcanic neck is exposed when the softer rock wears away.

23. Saint Michel D’Aiguilhe Chapel
Church built on Volcanic plug in France.

24. Devils Tower, WY.

25. This close up of
Devil’s Tower
shows columnar
jointing.

26. A dike forms when magma cuts across rock layers (vertical).

27. A sill forms when magma squeezes between rock layers (horizontal).

28. Batholith— formed when huge body of magma cools beneath the surface

29. Monitoring Volcanoes
Geologists have been somewhat more successful in predicting volcanic eruptions than in predicting earthquakes.
Geologists use tiltmeters, laser-ranging devices, and other instruments to detect slight surface changes in the elevation and tilt caused by magma moving underground.

30. …MORE
They also measure water levels in a crater’s lake, escaping gases from a volcano & underground water temperatures.
Geologists monitor the many small earthquakes that occur in the area around a volcano before an eruption. The movement of magma in the magma chamber and through the volcano’s pipe triggers small quakes.

31. Volcanic Hazards
Quiet and explosive eruptions can cause damage far from a crater’s rim.
During quiet eruptions, lava flows set fire and bury everything in their path.
Explosive eruptions can create hot burning clouds of volcanic gases as well as pyroclastic flows.

33. Ash Hazards
ash can bury entire towns, damage crops, collapse roofs, and destroy engines.
Eruptions can also cause landslides and avalanches of mud and melted snow.

34. Lava flows
are streams of molten rock.

35. How do you think these eruptions affected people?
Destroyed lives
Destroyed buildings
Destroyed crops
BUT, fertilized the soil with phosphate and potassium. This makes the soil excellent for farming.

36. Volcanoes of the Past
In history, there have been explosive volcanic eruptions. The following are two of the worst in history.
In 1883, Krakatau erupted violently throwing 18 cubic kilometers of ash into the sky. The blast was heard 5,000 miles away.
In 1902, Mt Pelee erupted releasing a cloud of gas which killed 29,000 people in TWO minutes. Only two people survived.

37. YouTube:
Live Eruption
Krakatau

38. Mt Pelee

39. Mt Vesuvius

40. In 1980, which volcano erupted after 123 years of being dormant?
Mt. St. Helens!

44. Lateral Blasts are explosive events in which gas and ash are
Ejected from the side of a volcano and travel
away from the volcano at velocities that
sometimes exceed the speed of sound.
YouTube:
Mt St Helen’s
Erupting