THE ROLE OF PHARMACOGNOSY IN TRADITIONAL AND MODERN SYSTEM OF MEDICINE.pptx
Volcanic Landforms and Features Explained
1.
2.
3. MAGMA
CHAMBER
A large underground pool of
liquid rock found beneath the
surface of the Earth. The
molten rock in such a
chamber is under great
pressure, and given enough
time, that pressure can
gradually fracture the rock
around it creating outlets for
the magma.
6. CRATER
Roughly circular depression
in the ground caused
by volcanic activity. It is
typically a bowl-shaped
feature within which occurs a
vent or vents
8. LAVA
A molten rock generated
by geothermal energy
and expelled through
fractures in planetary
crust or in an eruption,
usually at temperatures
from 700 to 1,200 °C.
12. PAHOEHOE
A smooth and continuous lava crust
Only low-viscosity lava can form pahoehoe
Lava flow that was originally pahoehoe may
transform into a’a lava
Pahoehoe is also known as ropy lava and it has
several more varieties named
Special conditions are needed for pahoehoe to
form: lava with low viscosity, low effusion rate,
and gentle slope.
14. A’A
A rough rubbly crust of a lava flow.
Walking on it is very slow and potentially
dangerous even if one has good hiking boot.
The uppermost part of a’a lava is composed
of loose unstable blocks
Flow rates exceeding 5-10 m3/s clearly
favors the formation of a’a lava
17. BLOCKY LAVA
Common if the silica content of
lava is higher.
They have irregular surfaces but
they contain larger lava blocks
with smoother sides and angular
edges.
19. PILLOW LAVA
A type of lava that is always associated
with water.
Form when lava flows out of the Earth’s
crust underwater
Usually demonstrate a convex upper and
concave or flat lower surface.
The surfaces of pillow lava are glassy.
20. VENTS
Spot in the Earth’s
crust where gases,
molten rock, lava
and rocks erupt
21. SILL
A flat piece of rock
formed when magma
hardens in a crack in
a volcano.
23. PARASITIC CONES
Cone-shaped
accumulation of volcanic
material that is not a part
of the central vent of a
volcano. It forms from
eruptions from fractures
on the flank of the
volcano.