--- title: "Topographical and geological maps for materials" subject: "Engineering Geology II" chapter: 7 key: "semester_4/engineering_geology_ii:maps-construction-materials" source: https://www.bctengineer.com/q/semester_4/engineering_geology_ii/maps-construction-materials site: BCT Engineering --- # Topographical and geological maps for materials Engineering Geology II · Chapter 7: Geology and Construction Materials - Asked in: 2078 Poush, 3 marks; 2076 Baisakh, 2 marks; 2070 Bhadra, 3 marks; 2081 Chaitra, 1.5 marks; 2069 Poush, 3 marks; 2070 Magh, 2 marks; 2068 Magh, 3 marks (asked 7 times) - Video: [Geological Maps and Their Application for Civil Engineering Works - Engineering Geology](https://www.youtube.com/watch?v=cJzgF1xK0sQ) — Ekeeda - Answer checked by Claude Opus 5.5 (high effort) on 2026-10-14 - Page: https://www.bctengineer.com/q/semester_4/engineering_geology_ii/maps-construction-materials - Whole chapter: https://www.bctengineer.com/md/semester_4/engineering_geology_ii/chapter-7 ## Question Describe the use (importance) of topographical (aerial) map, geological map and engineering geological map in searching for construction materials. ## Short answer Topographical maps locate accessible landforms (terraces, fans) and measure area. Geological maps show rock type, attitude, and extent to assess quality and reserve, avoiding faults. Engineering geological maps provide engineering properties, rock mass class, and hazards, allowing direct selection of safe, high-quality quarry sites. ## Answer Construction materials (aggregate, sand, gravel, boulders, clay, limestone) must be found close to the project, in sufficient quantity and quality. Maps are the first tools in this search. #### 1. Topographical (and aerial) map - Shows contours, rivers, terraces, slopes, roads, villages and land use, helping to locate accessible sites and estimate haul distance and area. - Shows landforms such as river terraces, fans and floodplains, which are likely sources of sand and gravel. - Aerial photographs and satellite images show vegetation, outcrops, river channels, landslides and tonal contrasts that indicate rock or soil types, and allow measurement of area. - Contours help to estimate overburden thickness, slope for quarry benches, and drainage. #### 2. Geological map - Shows the type, age and distribution of rock formations, and the attitude (strike and dip) of beds, faults, folds and contacts. - Helps to choose the formation suitable for aggregate (quartzite, limestone, granite, gneiss), cement raw materials (limestone, clay) or building stone, and to estimate thickness and extent, thus reserve. - Shows weak, shattered and weathered zones (faults, shear zones) to be avoided. #### 3. Engineering geological map - Shows rock/soil engineering properties, weathering grade, joint spacing, rock mass classes, slope stability, groundwater and geohazards. - Allows direct selection of the best site considering quality, safety of quarry slopes, stability and environment. - Shows areas to be avoided (landslides, active gullies, flood zones) and areas for waste disposal. **Together** the maps narrow the search from the regional scale to the quarry or borrow site, which is then confirmed by field mapping, test pits and laboratory tests. ## Check yourself The answer's key points as multiple-choice questions, with the correct option and why. 1. What do topographical maps and aerial photos contribute? A. Rock strength and joint spacing B. Landforms like terraces and fans, access, haul distance and area, plus overburden and slope estimates C. Strike and dip of beds D. Rock mass classes and groundwater Answer: B. Topographic and aerial data show landforms, access and area, but not rock structure or properties. (Key point: Topographic map use) 2. What does a geological map add? A. Only contour lines and roads B. Laboratory test results for each sample C. Flood zones and waste disposal sites only D. Rock type, distribution and attitude of beds, and weak zones such as faults to avoid Answer: D. It identifies suitable formations, estimates thickness and extent, and shows shattered zones. (Key point: Geological map use) 3. What distinguishes an engineering geological map? A. It shows only the age of formations B. It shows engineering properties, weathering, joints, slope stability and geohazards, allowing direct choice of the best site C. It replaces field and laboratory confirmation D. It shows only rivers and villages Answer: B. It combines quality and safety information; sites are still confirmed by field mapping and tests. 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