C4: GEOLOGICAL MAPS AND FOLDS, FAULTS, AND JOINTS Flashcards
provide a visual representation of the geology of a region, including rock types, faults, folds and other geological features.
Geological Maps
The purpose of these maps is to help geologists understand the geological history and structure of a given area, which can be used for a variety of purposes, such as mineral exploration, natural resource
management, and hazard assessment.
Geological Maps
are mapmakers who design user-friendly maps
Cartographers
are specialized mapmakers who use various technologies to build models of the Earth’s surface and its features for the purpose of creating maps.
Photogrammetrists
The history of geological maps can be traced back to the late __________, when geologists began to map out the geology of various regions.
One of the earliest geological maps was created by ____in 1815, which depicted the rock layers and coal seams in England and Wales.
18th century
William Smith
In the early _______, advancements in
technology, such as aerial photography and seismic surveys, allowed geologists to create more accurate and detailed geological maps.
20th century
5 TYPES OF MAPS
- BEDROCK MAPS
- SURFICIAL MAPS
- STUCTURAL MAPS
- MINERAL MAPS
- GEOLOGICAL HAZARD
These maps show the location and distribution of different types of rock formations at or near the Earth’s surface.
________ can be used to identify the age, composition, and structure of rocks in an area, as well as their potential for use as natural resources.
Bedrock maps
These maps show the distribution of different types of surficial materials, such as soils, sediments, and glacial deposits. __________ can be used to study the history of climate change, the location of natural resources like water and minerals, and the potential for soil erosion
and landslides.
Surficial maps
These maps show the orientation and location of different types of geologic structures, such as faults and folds. _________ can be used to study the history of tectonic activity in an area, as well as the potential for earthquakes and other natural hazards.
Structural maps
These maps show the location and distribution of different types of minerals and mineral resources in an area.___________ can be used to study
the geology of an area, as well as the potential for economic development through mining and other resource extraction.
Mineral maps
These maps show the potential for natural hazards, such as earthquakes, landslides, and volcanic eruptions, in an area. __________ can be used to identify areas that are at risk for these types of events, as well as to develop strategies for mitigating their effects.
Geologic hazard maps
10 COMPONENTS OF MAPS
- LEGEND/KEY
- SCALE
- NORTH ARROW
- CONTOUR LINES
- GEOLOGICAL FORMATIONS
- STRUCTURAL FEATURES
- CULTURAL FEATURES
- GRID LINES
- MARGINAL INFORMATION
- EXPLANATORY NOTES
A list or diagram that explains the symbols and colors used on the map, including rock formations, geological structures, and other features.
Legend/Key
indicates the relationship between distances on the map and actual distances on the ground.
Scale
A symbol that shows the orientation of the map, usually
pointing to true north.
North Arrow
Lines that connect points of equal elevation, used to depict the topography of the area
Contour Lines
Different rock units that are shown using distinctive colors or patterns, with each formation labeled according to its age and type.
Geologic Formations
Faults, folds, and other features that show how the rock layers have been deformed over time.
Structural Features
Lines that connect points of equal elevation, used to depict the topography of the area.
. Cultural Features
Lines that divide the map into sections to help with navigation and measurement.
Grid Lines
Additional information about the map, such as the date it was created, the name of the geologist who made it, and the source of the data used to create it.
Marginal Information
Additional information about the geology of the area, including the geological history, mineral resources, and other relevant details.
10.Explanatory Notes
are used to assess the geologic hazards associated with an area, such as landslides, sinkholes, and seismic activity. This information is essential for designing safe and effective infrastructure.
Geological maps
are bends or wavelike structures in rock layers caused by compressional forces. They occur when rocks behave plastically (ductile deformation) and do not break
FOLDS
4 TYPES OF FOLD
SYMMETRICAL FOLD
ASYMMETRICAL FOLD
OVERFOLD
RECUMBENT FOLD
Both limbs of the fold have equal angles relative to the axial plane, indicating uniform compressional forces from both sides.
SYMMETRICAL FOLD
The limbs exhibit different angles, suggesting unequal compressional forces during formation.
ASYMMETRICAL FOLD
One limb is tilted beyond the vertical, causing the layers to overlap, often due to intense compressional forces.
OVERFOLD
The axial plane is nearly horizontal, resulting in a fold lying on its side, typically found in regions with significant tectonic activity, such as mountain belts formed by plate collisions
RECUMBENT FOLD
are fractures in rocks along which movement has occurred. They result from brittle deformation and can be classified based on the direction of movement.
FAULTS
3 TYPES OF FAULTS
- NORMAL FAULT
- REVERSE FAULT
- STRIKE-SLIP FAULT
Occur due to tensional forces; the hanging wall moves down relative to the footwall
- Typically associated with divergent plate boundaries.
NORMAL FAULT
Form under compressional forces; the hanging wall moves up relative to the footwall.
- Often associated with convergent plate boundaries.
REVERSE FAULT
A strike-slip fault is a geological fault where the movement of tectonic plates occurs predominantly horizontally, parallel to the fault plane, in opposite directions, typically due to horizontal shearing forces.
- Are primarily associated with transform plate boundaries
STRIKE SLIP FAULT
are fractures in rocks where there is little to no movement. They form due to cooling, unloading, or tectonic stress. Unlike faults, _______ do not show significant displacement. They can occur in parallel sets and often influence weathering, erosion, and fluid movement in rocks.
joints
6 TYPES JOINTS
TECTONIC
EXTENSION
HYDRAULIC
EXFOLIATION
UNLOADING
COOLING
Formed by tectonic stresses and movements in the Earth’s crust.
Tectonic Joints
Form when rocks are subjected to tensile stress, pulling the rock apart, leading to the opening of cracks.
Extension Joints
Formed by the action of water, such as erosion or pressure
Hydraulic Joints
Formed by the release of pressure on rocks, such as when overlying rocks are removed.
Unloading Joints
Formed by the cooling and contraction of rocks, such as columnar jointing.
Cooling Joints
