UNIT 2

Hydrologic Cycle

It is the continuous circulation of water between the Earth’s spheres. It includes the aftermath of precipitation (A.K.A. rainfall or snow) falling on land. They either:

• Go through surface run-off

• Infiltration (Water absorbed into ground)

• Evaporate

• Absorb into plant and animal tissues

The four major ocean basins

Atlantic, Pacific, Indian, and Arctic Oceans.

Pacific Ocean

The largest and deepest ocean on Earth. It is half of the ocean surface area of Earth.

The Atlantic Ocean

2nd largest ocean. Half the size of the pacific, and not as deep. Is considered narrow and is in between the shores or margins of continents.

The Indian Ocean

3rd largest ocean. Smaller than the Atlantic but also as deep as it. Uniquely, it is a body of water part of the Southern Hemisphere.

The Arctic Ocean

The 4th largest, or the smallest ocean. Not as deep as the rest of the oceans.

Composition of Seawater

35% Salinity (Amount of solid materials dissolved in water). NaCl (Salt) along with other salt types comprise of 99% of the dissolved water in the sea.

Ocean Layering

1. Surface Mixed Zone: Warm and uniform temperatures.

2. Transition Zone: Includes a thermocline (transition between the warmer mixed zone water and cooler deep zone water.) and a pycnocline (separation between the two densities of the liquids.)

   1. Deep Zone: Cold and deep, 80% of all ocean water depth.

Freshwater sources

Usually in inaccessible areas such as high mountain tops and polar regions (glaciers). Readily available sources are found in surface water and ground water reservoirs.

Glaciers

Glaciers are formed from long lasting compaction of ice and snow that forms on land masses.

Ice Shelf

A floating extension of land ice.

Mountain Glaciers

A type of glacier that is formed on a mountain. There are different types of them, Cirque, Valley, Mountain Ice Cap, and Piedmont.

Continental Glacier

A type of glacier that covers a very, very, large mass of land (More than 50,000 square km) Only exists in Greenland and Antartica.

Surface Water

It is the lakes, streams, rivers, where water from rainfall and melting snow flows to.

Permafrost

A permanently frozen layer of ice on or under Earth’s surface.

Stream & River

Natural bodies of water that flow continuously in a channel into larger bodies of water such as oceans or lakes, usually down a slope.

Rivers are large streams that get water flown in through smaller streams called tributaries.

Meandering River

A river that is a continuous flow with twists and turns.

Braided River

A river channel that is made of smaller channels.

Lakes

• A large body of water usually enclosed by land masses. It occupies the depression of a land mass.

• Lake water comes from rain, melting snow and ice, and streams.

• They contain freshwater

Oligotrophic Lake

A deep like that lacks nutrients and is made of pure water, so it does not have many living life forms.

Eutrophic lake

A lake that contains an abundance of nutrients, sustaining living organisms.

Wetlands

Biologically diverse environments that sustain many living organisms. It remains flooded or soaked either through the year or in specific seasons. Includes:

• Swamps, marshes, mudflats, floodplains, Estuary

Swamps

A type of wetland that is dominated by lush trees and vegetation. It is found in low lying areas beside slow moving rivers.

Estuary

A wetland coastal area where freshwater from the river/stream meat saltwater from the ocean.

Marsh

A shallow wetland near lakes that are covered in grasses and weeds are dominant in vegetation.

Groundwater

Largest reservoir of freshwater for humans to use. Found underground. Comes from rain or snow, or water seeping into the ground

• Zone of Saturation: At the bottom where the water is located. It fills the pores and rock fractures.

• Zone of Aeration: Above the water table where the soil is mostly filled with air.

• Water Table: The boundary that separates groundwater from the surface

Porosity

The empty spaces between rock pores. High porosity = larger pores

Permeability

Ability of a rock for water or sediments to pass through. High permeability = more passes through

Aquifers

A body of rock that can hold a large quantity of groundwater. It has to be both porous and permeable.

Artesian Wells

A well drilled into a contained aquifer so waters can rise without pressure, and sometimes flow to the top for human consumption

Springs

When ground water’s water table is at the land surface, so it seeps to the surface and creates streams or small bodies of water.

Clean water act

The Philippines Clean Water act aims to protect natural bodies of water from pollution.

Order of the Earth’s layer

1. Crust

2. Mantle

3. Lithosphere

4. Asthenosphere

5. Core

Crust

The outermost layer of the earth

Mantle

Hot, slow flowing solid layer between the crust and the core

Lithosphere

The rigid outer layer of the Earth which consists of the crust and upper mantle

Asthenosphere

A zone in the mantle just below the lithosphere that behaves like a viscous fluid, which cause the mantle rock to be softest and weakest.

Core

The center of the Earth. The inner core is solid, the outer core is liquid.

Continental drift

Alfred Wegener suggested the theory that the super continent Pangea (which comprised of every continent stuck together) slowly drifted apart throughout millions of years. This movement is driven by tectonic forces and results in the current positions of continents.

Jigsaw Puzzle Piece

An evidence of the super continental drift theory | The coast of continents such as South America, Africa, and North America fit together like puzzle pieces. In theory, it demonstrates how they were once connected

Distribution of Fossils

An evidence of the super continental drift theory | Similar or same fossil types were found on different continents. It suggest that these animals were able to freely roam around the “Pangea” land mass.

Rock Type and Geological Features

An evidence of the super continental drift theory | Where coastlines are facing one another, mountain belts and similar geological structures appear across these continents.

Paleoclimate

An evidence of the super continental drift theory | Coal deposits have been found in areas that do not have tropical climate, proving that these continents have been moving around.

Rejection of the continental drift

No credible mechanism for the drift

Continents do not break through ocean floor

Tidal energy is too weak to displace large land masses

Theory of Tectonic plates

It is the theory that the lithosphere is divided into 7 major tectonic plates, and they move relative to each other on top of the asthenosphere.

Earth’s Major Plates

7 Large plates, 7 mid sized plates, and many small sized plates. They meet at boundaries that may either be divergent, convergent, or transform

Divergent Plate Boundaries (Constructive)

These are regions that move AWAY from each other, allowing magma from the inner Earth and generate new slivers of sea floor. However, this can also happen on land and not just the sea floor. They are characterized by volcanic activity and the formation of new crust as tectonic plates separate.

Convergent Plate Boundaries (Destructive)

Two plates that move against EACH OTHER. The leading edge slides on top while the other one is slide beneath it. There are three types, Ocean-ocean, Ocean-continental, and Continental-continental convergence

Oceanic-oceanic Convergence

A type of convergence that happens when two oceanic plates collide. The older one slides under, into the lithosphere. This process form volcanic island arcs.

Oceanic-Continental Convergence

A type of convergence that occurs when an oceanic plate and a continental plate collide. The oceanic one slides underneath, and volcanoes form on the continental plate.

Continental-Continental Convergence

A type of convergence that happens when two continental plates collide, forming a new mountain belt.

Transform Plate boundaries

Lithospheric plates that slide against each other, side to side as divergence or convergence happens.

Testing the plate tectonics model

Includes ocean drilling, mantle plume and hotspot, and paleomagnetism.

Ocean Drillng

A method that has found out that age of the sea floor increases with distance from a mid-ocean ridge. It involves extracting core samples from the ocean floor to study geological and biological processes.

Mantle Plume & Hotspot

Hotspot: An area of volcanic activity where a mantle plume reaches the surface. Volcanism provides evidence of both the direction and rate of plate movement over time.

Paleomagnetism

Rock layers which change relative to the Earth’s magnetic field and poles over time.

Why do great slabs of lithosphere move

They move due to convection. Convection refers to the circulating fluid in response to heating and cooling. Convection in the mantle move the fluid in different direction, moving the lithosphere in a process called subduction. The cooler, older, denser edge of the lithosphere sinks back into the mantle.

Earthquake

The ground shaking as a result of the sudden and rapid movement of tectonic plates rubbing against each other along fractures in the Earth’s crust (faults)

Hypocenter

Location in the Earth’s crust where an earthquake originates. AKA Focus.

Epicenter

The point on the Earth’s surface directly above the hypocenter.

Directions of fault movements

Faults: fractures in a rock with movement along them can occur in several directions, including horizontal, vertical, or oblique movements.

Causes of Earthquakes

Elastic rebound: Stress of rocks which cause it to fracture, and rebound as soon as it is broken.

Seismology

The study of Earthquakes and Earth’s interior based on evidence from seismic waves

Seismograph

Records seismic waves.

Seismograph

Physical or digital record of earthquake waves as measured by a seismograph.

Seismic waves

Waves of energy generated by earthquakes. Two types, namely: Surface and body waves.

Body waves

Seismic waves that travel through the Earth's interior, including primary (P) waves and secondary (S) waves. Faster than Surface waves

P waves

A type of body wave. When rocks are compressed in the direction of travel. CAN travel through solid, liquid, and gas. Fastest wave

S Waves

A type of body wave. Moves in the perpendicular direction of travel. Like a snake motion. Can ONLY pass through solids, not liquids and gases.

Surface waves

Only move through the Earth’s surface. Include Rayleigh waves and love waves. They are responsible for most of the damage during an earthquake due to their amplitude and duration.

Rayleigh Waves

A type of surface wave. Compress and dialate near the surface. Perpendicular to direction of travel.

Love waves

A type of surface wave that causes back and forth shear motion in a horizontal plane, moving side to side.

Modified Mercalli Scale

A scale that measures the intensity of an earthquake based on the damage it causes to buildings and people.

Richter Scale

Measures an earthquake’s intensity based on the amplitude of the largest seismic wave recorded on the seismogram

Tectonic Stress

The force exerted against an object. Rocks can deform elastically or plastically. Creates three structures: Folds, faults, and joints

Compressional Stress:

Squeezes rock together.

Tensional Stress

Stretches rock apart

Shear Stress

Causes sliding and tearing of rock mass.

Folds

A bend in rock layers caused by compressional stress, resulting in various shapes and structures. Parts:

• Limbs: Side of a fold in a rock

• Anticline: Fold in a rock that arches upward

• Syncline: Fold that arches downward

Fault

A fracture in rock where movement has occurred, typically caused by stress, resulting in displacement of the rock on either side.

Joints

Fractures in rock where no movement has occurred, often leading to secondary processes like weathering and erosion.

Volcanism

The process of magma movement from beneath the Earth's surface to create volcanic eruptions, including the formation of volcanoes and lava flows.

Viscosity of lava

Differences based on silica content; high silica = more viscous.

Types of Lava Flows

• Pahoehoe: Smooth, ropy lava.

• Aa: Rough, jagged lava flow.

Magma Formation and Eruptions

Magma formation occurs when heat and pressure cause rocks in the Earth's mantle to melt, leading to volcanic eruptions when magma reaches the surface.

Conditions for Melting

Increase in temperature, lower pressure, and addition of water can lead to melting of solid rock.These conditions decrease the melting point of rocks, facilitating magma formation.

Normal fault

Reverse Fault

Thrust Fault

Right-Lateral-Strike-Slip fault

Erosion

It is the process where weathered sediments are transported after weathering by agents of erosion.

Main agents of erosion

Water, wind, glacier

Splash erosion

A water agent of erosion | When raindrops cause soil to detach from its main mass, and jump out into another area

Sheet erosion

A water agent of erosion | Raindrops break apart the soil structure and create a thin layer of soil loss across a large area, often moving down a slope

Gully erosion

A water agent of erosion | After heavy rain, water flows into small channels, further eroding it and forming a deeper dent into the Earth.

Valley erosion

A water agent of erosion | Downward movement of water along multiple slopes into a common ditch, further deepening the valley.

Bank erosion

A water agent of erosion | When the continuous flow of water erodes the banks (edge/side) of streams and rivers.

Coastline erosion

A water agent of erosion | When waves from the sea crash into a coastline, breaking it down into rocks and carrying the sediments into the ocean.

Seaside cliff erosion

A water agent of erosion | When ocean waves batter the base of seaside cliffs, boring holes into the rock, creating waves

Glacier Erosion

When rocks embedded into the ice scrape bedrock, cutting deep parallel grooves. Can erode land through plucking and abrasion