Springshed Management Training Curriculum

2016The Springs Initiative

Springshed Management Training Curriculum, Draft 2

SESSION TITLE:

Fundamentals of Geology

SECTION: Understanding the ResourceMODULE: I. Why Springs & Basic HydrogeologyAUTHORS: Kaustubh Mahamuni, Dr Himanshu Kulkarni, Dr Jared BuonoCONTRIBUTING ORGANIZATIONS: Acwadam, Arghyam PURPOSE: A basic overview of geologic concepts as foundation for hydrogeologyIMPACT: Participants will learn about the rock cycle, rock types, structures, primary versus secondary porousityTIME REQUIRED: 90 minutesMATERIALS: This pptADDITIONAL RESOURCES:

Outline:

• Tectonics

• Rock cycle

• Rock types

• Geologic structure

Springshed Management Training Curriculum, Draft 2

Ground water occurs in

openings in the rocks that

form the Earth’s crust. The

volume of the openings and

the other water-bearing

characteristics of the rocks

depend on the mineral

composition, age, and

structure of the rocks.

Therefore, geology is key to

understanding groundwater

and springs

Source: www.lifeinuniverse.org

600 °C

• The earth is not solid or homogenous

• Different layers of varying viscosity

• Heat, rotation, convection cause circulation

• Leads to movement of surface plates

• Entire planet is covered in crust plates

• Continental versus oceanic

• India is its own plate

• Has been colliding with Asia, cause of Himalayas

• These movements cause cycling materials

• The rock cycle

Minerals and Rocks

Sedimentary Rocks

• Erosion and deposition of weathered rocks, soil, organic matter

• Accumulates and is cemented via pressure of overlain sediments

• Can be by wind, water

• Sands are deposited in and near delta -sandstone

• Fine silt and clay out to sea – shale

• Limestone from shallow warm seas (sea shells)

• Coal from swamps – high carbon content

LimestoneCredit: pitt.edu/~cejones/GeoImages/

ShaleCredit: pitt.edu/~cejones/GeoImages/

ucdenver.edu

Igneous Rocks

• Meaning ‘of fire’

• Magma or lava – molten rock

• Can be intrusive• Magma that

cools below surface

• granite pluton

• Or extrusive• volcanic, lava

is molten rock that forms on surface

• basalt

Intrusive or Plutonic Igneous rocks

•Magma collects and pools.

•It looses temperature

slowly to the surrounding

rocks.

•Big, well-formed crystals.

Visible mineral grains, massive texture, no foliation or layers

Intrusive or Plutonic Igneous rocks

Extrusive or Volcanic Igneous rocks

•Lava comes out as flows

•It comes in contact with air and water.

•Cools rapidly.

•Solidifies immediately.

•Crystals formed are very small.

Photo courtesy of US Geological Survey; Hawaiian Volcanoes Observatory, Hawaii Volcanoes National Park, August 10, 2002

Molten Lava, Kilauea Volcano, Hawaii

Water vapor and carbon dioxide are the principal gases dissolved in a magma.More than 90% of the gas emitted from hot magma is water (H2O) and carbondioxide (CO2).

Magma /lava

Metamorphic Rock systems

Source: Earth’s Dynamic Systems

Granite Gneiss

• Under pressure and temperature

• Undergoes solid-state change

• Minerals are compressed or stretched

• Lineated or foliated

• Gneiss is a common rock in Meghalaya

Granite (igneous rock) Gneiss (metamorphic rock)

Credit: pitt.edu/~cejones/GeoImages/

Credit: pitt.edu/~cejones/GeoImages/

• Sandstone metamorphosis –quartzite

• Heat and pressure – solid state change

• Grains no longer visible

Source: Earth’s Dynamic Systems

Metamorphism of Shale

Common Rock Types

Sedimentary Rocks

SandstoneShale

LimestoneConglomerate

Grit

Metamorphic Rocks

GneissSchist

QuartziteSlate

MarbleAmphibolite

Igneous Rocks

GraniteBasalt

ObsidianPumiceRhyoliteGabbroDolerite

So how do u identify a rock ????

• Rocks are grouped together based on similar processes of

formation to give us 3 types of rocks.

• Color

• Texture

• Minerals

Physical & Chemical

properties

The attitude of openings determine the direction in which

the water will move.

The size of openings would decide the ease with which water

would move in the rock.

Ease of movement of water in the rock is termed permeability.

•Folds•Faults•Joints

Rocks deform in response to

differential stress. The resulting

structure depends on the stress

orientation.

Deformation may be ductile flow

or brittle fracture.

Structure in rocks

Compression

Tension

Shear

Image source: ssf.npolar.no

Small folds

Medium folds

Large folds

Landscape-scale folds

Anticline

Types of folds

Anticline

Types of folds

Syncline

Types of folds

Syncline

Types of folds

- Fracture in the Earth's crust, on either side of which rocks have moved past each other.- Faults may occur where rocks are being pushed together (compression) orpulled apart (tension) by plate tectonics, movements of the plates of the Earth's crust.-Large movements cause detectable earthquakes

Tension

Hanging wallFoot wall

Normal Fault

Faults

Thrust fault

Compression

Hanging wall

Foot wall

Strike slip faultShear

Faults

Joints• Caused by cooling lava• Can be vertical or horizontal• Relatively small in length• Can be very productive locally

• These differences in rock type and structure lead to differences in ability to store & transmit water

• Affects aquifers, springs & in this photo, the vegetation and ecology – gallery forests