geology

1. The Force of Geology-Part Two
Endogenic and Exogenic Process
Widodo, S.T., M.T.
Mining Geology SMK N 1 Balikpapan
Volcanic

2. Volcanic Activity
 Magma
 Molten rock underneath the earth
 Lava
 Molten rock reaching Earth’s surface
 Volcano
 Surface vent for lava

3. Volcano Types
 Shield volcanoes
 Sedate
 Runny lava
 The Hawaiian Islands: Mauna Loa, Hawaii (still
active, but not explosive)
 Composite cone volcanoes
 Explosive
 Pyroclasts – this explosive material includes sticky
lava, hot ash, sulfurous gas, rock bombs, etc – e.g.
Pompei
 Krakatau in Indonesia, largest recorded eruption.

6. Tectonic-Volcanic

7. Volcanic Product

8.  Three factors effect the explosivity of a volcano
 Temperature of magma
 High-temperature, less explosive
 Composition of magma
 Less silica, less explosive
 Gas content of magma
 Less gas, less explosive
fluidity
Volcanic Eruption

10. Product of Effusive Eruption
low viscosity, low gas content
Hawaiian type
Smooth Ropey
pahoehoe surfacerough rubbly
surfaces A’a

11. med - high viscosity, high gas content
pumice Volcanic ash
Names for pyroclastic
rocks based on clast size
or tephra
Pumice is formed as pyroclastic
material is ejected into the air as a
froth containing masses of gas
bubbles or vessicles, the lava
solidifies quickly and the vessicles
are contained in the rock.
Product of Explosive Eruption