---
title: "Volcano and positive topography"
subject: "Engineering Geology I"
chapter: 6
key: "semester_3/engineering_geology_i:volcano-and-positive-topography"
source: https://www.bctengineer.com/q/semester_3/engineering_geology_i/volcano-and-positive-topography
site: BCT Engineering
---

# Volcano and positive topography

Engineering Geology I · Chapter 6: Physical Geology

- Asked in: 2074 Chaitra, 2 marks
- Video: [VOLCANIC TOPOGRAPHY (ENGLISH) (WITH NOTES)](https://www.youtube.com/watch?v=50s_uapea9k) — STUDY FOR KNOWLEDGE 
- Answer checked by Claude Opus 5.5 (high effort) on 2026-10-14
- Page: https://www.bctengineer.com/q/semester_3/engineering_geology_i/volcano-and-positive-topography
- Whole chapter: https://www.bctengineer.com/md/semester_3/engineering_geology_i/chapter-6

## Question

What is volcano? Discuss the positive topography developed by volcano.

## Short answer

A volcano is a crustal vent that erupts magma, gases and ash, forming a hill or mountain. Positive landforms include cinder cones, composite cones, shield volcanoes, lava domes, lava plateaus, and exposed volcanic necks, dykes and sills.

## Answer

A **volcano** is a vent in the crust through which magma, gases and ash erupt, and the hill or mountain built around it.

#### Positive topography developed
- **Cinder (scoria) cone:** small steep cone of loose ash and cinders.
- **Composite (strato) cone:** large steep cone of alternate lava and ash, e.g. Mt. Fuji.
- **Shield volcano:** broad low dome of fluid basalt, e.g. Mauna Loa.
- **Lava dome (plug dome):** steep mound of viscous lava.
- **Lava plateau:** wide flat area from fissure flows, e.g. Deccan Traps.
- **Ash and tuff plains, volcanic necks, dykes and sills** exposed by erosion.

Negative forms are craters, calderas and lava tubes.

## Check yourself

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

1. A volcano is:
   A. A fold in rock layers formed by compression
   B. A deep trench in the ocean floor
   C. A vent in the crust through which magma, gases and ash erupt, and the hill built around it
   D. A river valley in hard rock
   Answer: C. The term covers both the vent and the built-up mountain. (Key point: Volcano)

2. Which volcano is a broad low dome built of fluid basalt?
   A. Composite cone, e.g. Mt. Fuji
   B. Cinder cone
   C. Lava dome
   D. Shield volcano, e.g. Mauna Loa
   Answer: D. Runny basalt spreads widely, giving gentle slopes. (Key point: Shield volcano)

3. A composite (strato) cone is made of:
   A. Alternate layers of lava and ash, forming a large steep cone
   B. Only loose cinders
   C. Only fluid basalt
   D. Only viscous lava plug
   Answer: A. Mt. Fuji is the example given. (Key point: Composite cone)

4. Which is a negative volcanic form rather than a positive one?
   A. Lava plateau
   B. Caldera
   C. Cinder cone
   D. Lava dome
   Answer: B. Craters, calderas and lava tubes are negative forms. (Key point: Positive vs negative)