---
title: "Strike of quartzite bed, dip 80° towards N10°E"
subject: "Engineering Geology I"
chapter: 5
key: "semester_3/engineering_geology_i:strike-of-quartzite-bed-dip-80"
source: https://www.bctengineer.com/q/semester_3/engineering_geology_i/strike-of-quartzite-bed-dip-80
site: BCT Engineering
---

# Strike of quartzite bed, dip 80° towards N10°E

Engineering Geology I · Chapter 5: Structural Geology

- Asked in: 2080 Baisakh, 1.5 marks
- Answer checked by Claude Opus 5.5 (high effort) on 2026-10-14
- Page: https://www.bctengineer.com/q/semester_3/engineering_geology_i/strike-of-quartzite-bed-dip-80
- Whole chapter: https://www.bctengineer.com/md/semester_3/engineering_geology_i/chapter-5

## Question

A quartzite bedrock dips at an angle of 80° towards N10°E. Find out the strike of the bedrock with illustration.

## Short answer

Dip direction N10°E (azimuth 10°). Strike = dip direction ± 90°, yielding azimuths 280° and 100°, so strike is N80°W (S80°E).

## Answer

The strike is the direction of the horizontal line on the bed and it is always at 90° to the dip direction.

**Given**: Quartzite bedrock dips 80° towards N10°E. Dip direction = N10°E, azimuth = 10°.

$$
\begin{aligned} \text{Strike} &= \text{dip direction} \pm 90° \\ &= 10° - 90° = 280° \ \text{or}\ 10° + 90° = 100° \end{aligned}
$$

These two azimuths (280° and 100°) are the two ends of one line, so the strike is **N80°W (S80°E)**.

```text
                    N
         N80W \     |     / dip N10E
                \   |   /
                  \ | /
  W ----------------+--------------------- E
                    | \
                    |   \
                    |     \ S80E
                    S
   ( \ = strike line N80W-S80E,  / = dip direction N10E, at 90 deg to strike )
```

**Answer: Strike = N80°W (S80°E).**

## Check yourself

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

1. How is strike related to the dip direction?
   A. Strike is parallel to the dip direction
   B. Strike is at 45° to the dip direction
   C. Strike equals the dip amount
   D. Strike is at 90° to the dip direction
   Answer: D. Strike is the horizontal line on the bed, perpendicular to dip direction. (Key point: Strike vs dip direction)

2. What is the azimuth of the dip direction N10°E?
   A. 10°
   B. 170°
   C. 80°
   D. 350°
   Answer: A. Convert the quadrant bearing to an azimuth measured clockwise from north. (Key point: Azimuth conversion)

3. What is the strike for dip direction N10°E?
   A. N10°W (S10°E)
   B. N80°W (S80°E)
   C. N80°E (S80°W)
   D. N10°E (S10°W)
   Answer: B. Azimuth +/- 90° gives the two ends of one line, which is the strike. (Key point: Strike result)

## Related in Engineering Geology I

- [Strike of quartzite bed, dip 70° towards S20°E](https://www.bctengineer.com/question.md?key=semester_3%2Fengineering_geology_i%3Astrike-of-quartzite-bed-dip) — Engineering Geology I, chapter 5
- [Strike of quartzite bed towards S20°W](https://www.bctengineer.com/question.md?key=semester_3%2Fengineering_geology_i%3Astrike-of-quartzite-bed-towards) — Engineering Geology I, chapter 5
- [Strike of quartzite bed dipping S25°E](https://www.bctengineer.com/question.md?key=semester_3%2Fengineering_geology_i%3Astrike-of-quartzite-bed-dipping) — Engineering Geology I, chapter 5, asked 2×
- [Strike of limestone bed directed N20°E, dip 45°](https://www.bctengineer.com/question.md?key=semester_3%2Fengineering_geology_i%3Astrike-of-limestone-bed-directed) — Engineering Geology I, chapter 5
- [Strike of limestone bed, dip N40°W, 64°](https://www.bctengineer.com/question.md?key=semester_3%2Fengineering_geology_i%3Astrike-of-limestone-bed-dip) — Engineering Geology I, chapter 5
- [Strike of limestone bedrock dipping N31°W](https://www.bctengineer.com/question.md?key=semester_3%2Fengineering_geology_i%3Astrike-of-limestone-bedrock-dipping) — Engineering Geology I, chapter 5

## Related in other subjects

- [Reserve: quartzite apparent dips 1:9 and 1:12, 2.7 x 3.1 km](https://www.bctengineer.com/question.md?key=semester_4%2Fengineering_geology_ii%3Areserve-quartzite-apparent-dips-terrain) — Engineering Geology II, chapter 7, asked 2×
- [Reserve: quartzite apparent dips 1:9 and 1:12, 4.6 km2](https://www.bctengineer.com/question.md?key=semester_4%2Fengineering_geology_ii%3Areserve-quartzite-apparent-dips-area) — Engineering Geology II, chapter 7, asked 2×
- [True dip from two apparent dips](https://www.bctengineer.com/question.md?key=semester_4%2Fengineering_geology_ii%3Atrue-dip-from-apparent-dips) — Engineering Geology II, chapter 6