Mountain Building—or what geologists call orogeny—is Earth’s way of flexing its strength and sculpting breathtaking landscapes over millions of years. Convergent Boundaries: This is the main driver. When two tectonic plates collide, they don’t just crash—they crumple. If both are continental plates, the land buckles and rises. Examplehe Himalayas, formed from the collision between the Indian and Eurasian plates. Subduction Zones: When one plate slides beneath another, magma can rise and form volcanic mountain ranges. Example: The Andes Mountains in South America.

1. OROGENY
MOUNTAIN BUILDING

5. How mountains are formed?
1. Accumulation of sediments
2. Folding and Uplift (Orogeny)
3. Erosion and isostatic rebound

6. 1. Accumulation of sediments

7. 1. Accumulation of sediments
Weathering & Erosion: Mountains or other
landforms erode over time due to wind,
water, and ice, producing sediments.
Transport: These sediments are carried by
rivers, wind, or glaciers and deposited in
low-lying areas called basins.
Layering: Over millions of years, layers
upon layers of these sediments build up—
sand, silt, clay, and organic material
compact into sedimentary rock.

8. How mountains are formed?
1. Accumulation of sediments
2. Folding and Uplift (Orogeny)
3. Erosion and isostatic rebound

9. 2. Folding and Uplift (Orogeny)

10. 2. Folding and Uplift (Orogeny)
When sedimentary rock layers are
compressed by tectonic forces, they don’t
always crack—sometimes they bend
instead.
There are different types of folds:
Anticlines: upward-arching folds
Synclines: downward-trough folds
Folding typically happens deep
underground where rocks are hotter and
more flexible.

11. How mountains are formed?
1. Accumulation of sediments
2. Folding and Uplift (Orogeny)
3. Erosion and isostatic rebound

12. In mountain building:
Erosion carves valleys and sharpens
peaks.
It removes material from high elevations
and transports sediments to lower areas
or oceans.
Surprising twist:
By removing weight from the mountain,
erosion actually contributes to raising it—
thanks to isostatic rebound.
3. Erosion and isostatic rebound

15. 1. What are
the types
of
mountains
and how
do you
describe
them?
2. Why plate
movement
s are
important
to study?

22. CHECKPOINT
Find a pair. Answer these questions
1. What is orogeny?
2. How is mountain building
associated with plate
tectonics?
3. What is the difference between
folds and faults?