UNIT 2 The Earth’s
Crust: is the thinner and solid layer of Geosphere, made up of rocks and minerals, it is the
outermost part of Geosphere.
IGP: they are produced by the Earth’s internal energy which produces the movement of tectonic
plates and as a result causes or provokes earthquakes, volcanoes, mountain formation... These
processes are called CONSTRUCTIVE GEOLOGIC PROCESSES (“they make relief”).
Continental shelf: it´s a part of continent that extends beyond shoreline, under the ocean.
Slope : it´s a big depression that extends from continental shelf to the sea floor.
Rift: it is the axis of a mid ocean ridge.
Abyssal plain: it´s the bottom of the ocean.
Lithospheric plates: They are fragments of crust .
Volcano: it is an opening of the surface of the Erath where gases, liquid and solid from the
asthenosphere are released.
Earthquake: they are vibratory movement of the Earth´s crust produced by releasing of
accumulated energy inside the Earth because of the contact/touch of tectonic plates.
Fold: it is the result of compression strengths on the ground. As a consequence concave an convex
waves are formed.
Fault: it is a rift in the ground that implies the displacement of both block formed.
Volcano Intensity : it is the magnitude that measures the strength with which a earthquake shakes
Volcano magnitude: it is the quantity released energy from focus.
Geothermal gradient : it is the rate of increasing temperature with respect to increasing depth in
the Earth’s interior.
MID OCEAN RIDGE
DEEP SEA TRENCH
3. Why is not the Asthenosphere considered as a real layer?
Because it is not a continuous layer
4. What is the difference between the lithosphere and the crust?
Lithosphere is a layer that belong to dynamic model, it is includes crust and a part of
5. Why does dynamic model appear?
Dynamic model appears to explain the movement of tectonic plates
6. Explain in detail the Continental Drift Theory?
Continental drift is the theory proposed by A. Wegener to explain the lithospheric
plates movement. According to this theory, 200 million years ago, there was a gigantic
super continent called Pangea (all-Earth). Pangea started to break up into smaller
super continents to form the continents which we know nowadays. Since then,
continents go on moving and changing their positions.
7. Alfred Wegener proposed four evidences or data to prove his
theory. Resume these evidences in four simple sentences. You
can use this table:
1. The shapes of continents fit as a puzzle
2. Similar rocks and geologic materials located in places too far away nowadays
(South American plate and African plate)
3. Distribution of similar fossils located in places too far away nowadays
4. Evidences of tropical climates in the current polar areas and vice versa
8. What are the causes of the Earth’s internal activity?
The causes are three: the Earth’s internal heat, semi-molten materials and as a
consequence, the convention currents formed.
9. Name the three types of plate boundaries and explain how
There are three types of boundaries:
• Convergent boundaries: the plates move toward each other. In general, one of the
plates subside beneath other and sink inside the mantle. These boundaries are
called destructive boundaries because they destroy lithosphere.
• Divergent boundaries: the plates move away from each other because of material
that rises from mantle through the rift (in ridge). These boundaries are called
constructive boundaries because they form new lithosphere.
• Transform fault boundaries: plates slide past each other, they move laterally in
opposite directions. No lithosphere is created or destroyed
10. Explain how is convection current formed
Heat from the Earth’s core heats up the material of lower mantle, these materials rise
because they are lighter. When they rise, they cool down and fall because they are
heavier. So convection currents are formed.
11. RESEARCH: Pacific ring of fire is an area located on Pacific
plate. This area is famous because of its volcanic an seismic
activity. What do you think is the cause of this activity?
The cause of activity in Pacific Ring of fire is that Pacific plate subduces and sinks
under American plate, Indo-Australian plate and Eurasian plate. They are
convergent boundaries, destructive boundaries that causes big seismic and
12. If an explosion is produced….
a. Which seismic waves arrive first?
b. If S waves don’t arrive, what can we deduce?
c. L and R waves aren’t interesting to study the Earth’s
a. P waves
b. We can deduce that there is a fluid area (fluid material) as S waves can’t travel
through fluid materials
c. Because they are surface waves. The don’t travel toward the Earth’s interior.
13. How do you explain....:
a. …that Japan is a country where earthquake are frequent?
b. …that Brazilian coast don’t have many earthquakes?
c. … the origin of mountain chain The Andes?
a. Because Japan is in a convergent boundary: Pacific plate subduces beneath
b. Because Brazil is “close” to a divergent boundary (Mid Atlantic Ridge)
c. Because Pacific plate subduces beneath South American plate (convergent b.)
14. RESEACH: find out information about Rift Valley in Africa.
Explain the process that is happening there.
It is a valley placed in East Africa. There, the origin of a divergent boundary is
happening. The African plate is breaking into two plates because of The Earth’s
internal energy; it’s the beginning of a new ocean.
15. True or false: rewrite the sentences correctly
A. The increasing of temperature inside Earth always rises at the same speed (rate) F
The increasing of temperature inside Earth DOESN’T rise at the same speed (rate)
B. Lithospheric plates are formed in convergent boundaries F
Lithospheric plates are formed in DIVERGENT boundaries
C. Asthenosp is a continuous layer made up of rigid material but it has fluid behaviour F
Asthenosp is a DISCONTINUOUS layer made up of rigid material but it has fluid
D. We can see seismic waves in a seismograph F
We can see seismic waves in a SEISMOGRAM
E. The most dangerous volcanoes are the ones that have very viscous lava and big
quantity of gases T
F. Lithosphere includes crust and part of lower mantle F
Lithosphere includes crust and part of UPPER mantle
G. Alfred Wegener proposed Tectonic Plates Theory F
Alfred Wegener proposed CONTINENTAL DRIFT THEORY
16. Draw a table in you notebook and match the terms of the two
Oceanic ridge, creation of lithosphere, oceanic trench, destruction of
lithosphere, the lithosphere is neither creates or destroyed, conservative
Transform fault boundaries, convergent boundaries, divergent boundaries
3 Ocean ridge
3 Creation of lithosp
2 Oceanic trench
Transform fault B.
2 Destruction of lithosp
1 Lithosp is neither
creates or destroyed