---
title: "Plate boundary and mountain formation"
subject: "Engineering Geology I"
chapter: 2
key: "semester_3/engineering_geology_i:plate-boundary-and-mountain-formation"
source: https://www.bctengineer.com/q/semester_3/engineering_geology_i/plate-boundary-and-mountain-formation
site: BCT Engineering
---

# Plate boundary and mountain formation

Engineering Geology I · Chapter 2: Basic Reviews of the Earth

- Asked in: 2073 Shrawan, 3 marks
- Video: [How Do Mountains Form?: Crash Course Geology #11](https://www.youtube.com/watch?v=r8uQVRVNV14) — CrashCourse
- Answer checked by Claude Opus 5.5 (high effort) on 2026-10-14
- Page: https://www.bctengineer.com/q/semester_3/engineering_geology_i/plate-boundary-and-mountain-formation
- Whole chapter: https://www.bctengineer.com/md/semester_3/engineering_geology_i/chapter-2

## Question

Describe plate boundaries. How is a mountain formed?

## Short answer

Plate boundaries are divergent (apart, new crust), convergent (together, subduction/collision) and transform (slide). Mountains form mainly at convergent boundaries where thick geosynclinal sediments are compressed, folded, faulted and uplifted, then shaped by erosion.

## Answer

#### Plate boundaries
The lithospheric plates meet at three types of boundary.
- **Divergent**: plates move apart; new crust forms (mid-ocean ridges, rift valleys).
- **Convergent**: plates move together; subduction or collision (trenches, island arcs, fold mountains).
- **Transform**: plates slide past each other (San Andreas Fault).

#### Formation of mountains
Mountains are mainly formed at convergent boundaries.
1. Thick sediments collect in a long, sinking trough (geosyncline) at a plate margin.
2. Plates move together and compress the sediments.
3. The layers are folded, faulted and thrust upwards, with metamorphism and igneous intrusion.
4. Uplift and erosion then shape the range.

Examples: Himalaya (continent-continent collision), Andes (ocean-continent subduction). Other mountains are formed by volcanism (Fuji) and block faulting.

## Check yourself

The answer's key points as multiple-choice questions, with the correct option and why.

1. The three boundaries are:
   A. Fold, fault, joint
   B. Crust, mantle, core
   C. Rift, ridge, trench only
   D. Divergent, convergent, transform
   Answer: D. Standard classification. (Key point: Boundary types)

2. Mountains mainly form at:
   A. Convergent boundaries
   B. Divergent boundaries
   C. Transform boundaries
   D. Mid-ocean ridges
   Answer: A. Compression. (Key point: Mountain site)

3. Mountain building sequence starts with:
   A. Erosion
   B. Sediments collecting in a geosyncline
   C. Metamorphism
   D. Intrusion
   Answer: B. Then compression, folding, uplift. (Key point: Sequence)

## Related in Engineering Geology I

- [Plate tectonics and plate boundaries](https://www.bctengineer.com/question.md?key=semester_3%2Fengineering_geology_i%3Aplate-tectonics-and-plate-boundaries) — Engineering Geology I, chapter 2, asked 8×
- [Constructive and destructive boundary; Himalaya formation](https://www.bctengineer.com/question.md?key=semester_3%2Fengineering_geology_i%3Aconstructive-and-destructive-boundary-himalaya) — Engineering Geology I, chapter 2
- [Convergent versus divergent plate boundary](https://www.bctengineer.com/question.md?key=semester_3%2Fengineering_geology_i%3Aconvergent-versus-divergent-plate-boundary) — Engineering Geology I, chapter 2, asked 3×
- [Himalaya formation and plate tectonic evidence](https://www.bctengineer.com/question.md?key=semester_3%2Fengineering_geology_i%3Ahimalaya-formation-and-plate-tectonic) — Engineering Geology I, chapter 2
- [Transform versus divergent plate boundary](https://www.bctengineer.com/question.md?key=semester_3%2Fengineering_geology_i%3Atransform-versus-divergent-plate-boundary) — Engineering Geology I, chapter 2
- [Formation and evolution of the Himalaya](https://www.bctengineer.com/question.md?key=semester_3%2Fengineering_geology_i%3Aformation-and-evolution-of-the) — Engineering Geology I, chapter 2, asked 5×

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