Earth Materials: Elements and Minerals

Earth Materials

• The geosphere consists of rocks, which are made of minerals, which are made of elements.
• Elements are composed of atoms with a nucleus containing positive protons and neutral neutrons, circled by negative electrons and cannot be broken down.
• Eight elements compose over 98% of the geosphere's mass.
• An ion is an atom with a positive or negative charge due to the loss or gain of electrons.
• An isotope is an atom with the same number of protons as other varieties of the same element but a different number of neutrons.

Abundant Elements in Earth's Crust

• Oxygen makes up 47%.
• Silicon makes up 28%.
• Aluminum makes up 8.1%.
• Iron makes up 5%.
• Calcium makes up 3.6%.
• Sodium makes up 2.8%.
• Potassium makes up 2.6%.
• Magnesium makes up 2.1%.

Minerals

• Minerals are consumed worldwide in billions of tons annually.
• A mineral is naturally occurring, inorganic, solid, has a specific chemical composition, and has a characteristic crystalline structure.
• Mineral dusts can cause diseases, exacerbated by smoking.
• Pneumoconiosis involves the deposition of particulate matter in the lungs, leading to inflammation.
• Asbestos is a term for hydrated silicate minerals that crystallize in a fibrous habit and can cause health problems if inhaled.
• Fibrogenic diseases can be fatal. Disease examples include "Black Lung" caused by silica and carbon inhalation.
• Malignant neoplasms (cancer) are often fatal.

Rocks

• Rocks are naturally occurring aggregates of one or more minerals and the mineral assemblage describes the variety and abundance of minerals present in a rock.

Igneous Rocks

• Igneous rocks form from the solidification of lava or magma and are the most common rock family.
• Extrusive rocks cool quickly above Earth's surface and are fine-grained.
• Intrusive rocks cool slowly below Earth's surface and are coarse-grained.

Sedimentary Rocks

• Sedimentary rocks form from the consolidation of sediments transported by water, wind, or ice, or deposited by organisms and are layered or stratified.
• Sediment is particulate matter that can be transported by fluid flow.
• Clastic sediment is made up of loose fragments of rock debris.
• Chemical sediment precipitates from solution in water.
• Biogenic sediment is made up of fossilized remains of organisms.

Metamorphic Rocks

• Metamorphic rocks form from the alteration of pre-existing rocks in response to high temperature and pressure and preserve evidence of the former rock type.
• Metamorphism is affected by the rock's chemical composition, changes in temperature and pressure, the presence of fluids, and time.

Rock Cycle

• The rock cycle explains how rocks are continually recycled and changed into new types.
• Weathering is the set of physical and chemical processes that change rocks at Earth’s surface.
• Physical weathering breaks rocks into smaller pieces, increasing the surface area to volume ratio.
• Chemical weathering breaks down rock and changes its composition.
• Erosion is the transportation of geosphere materials by water, wind, ice, and gravity.

Earthquakes - Function and Movement

• Earthquakes are trembling or shaking of the Earth, caused by tectonic movements within the lithosphere and generate seismic waves.
• Earthquake focus is where the energy is released and the epicenter is the location on the surface above the focus which are classified by depth of focus.
• Largest earthquakes occur along subduction zones and generate tsunamis.
• Transformed plate boundaries involves system of connected faults.
• Divergent boundaries cause small to moderate earthquakes.
• Intraplate boundaries can also experience earthquakes.
• Faults are fractures in rocks along which movement occurs.
• Elastic Rebound Theory states that earthquakes result from the release of stored energy by slippage on faults.
• Earthquake (or seismic) waves are vibrations that travel through the Earth or along its surface.

Earthquake Waves

• Surface waves move along Earth’s surface.
• Body waves travel through the Earth.
• P Waves are compressional waves that can be transmitted through liquids and solids.
• S Waves are shear waves that can only be transmitted through solids.

Studying and Measuring Earthquakes

• Seismometers measure magnitudes of earthquakes and locate fault ruptures.
• 3 Seismometers are required to locate the epicenter using P and S waves.
• A seismogram is a recording of ground motions caused by seismic waves.
• Satellites can measure changes in land surface in seismic zones.
• The Richter Scale measures displacement on a fault to estimate earthquake magnitude.
• Moment Magnitude accounts for displacement and the length of the rupture area and is the most commonly used scale by scientists
• The Modified Mercalli Index is based on the amount of damage / What is felt in a specific area during an earthquake,.

Hazards Associated with Earthquakes

• The intensity of ground shaking and movement depends on quake size, distance from focus, and site geology.
• Ground motion is especially dangerous in soft sediments that amplify the vibrations.
• Liquefaction occurs when water-saturated sediment is shaken, turning it into a liquid.
• Earthquakes can trigger mass wasting events in areas with steep slopes.
• Tsunamis form when water is displaced above a sudden offset on the seafloor and slow down and gain height as they enter shallow water.

Earthquake Occurrence and Forecasting

• The most powerful earthquakes in history have mostly occurred at subduction zones.
• The deadliest earthquakes are not always the most powerful earthquakes.
• Earthquakes in the East cause more ground motion and shaking because the bedrock is older and therefore more rigid.
• Earthquake Forecasting involves identifying earthquake-prone buildings and areas.
• Seismic Gaps are used to suggest areas that are "overdue" for earthquakes.

Rivers and Flooding

• A stream is a body of water that flows downslope along a clearly defined natural pathway.
• A channel is the passageway the stream flows through.
• The goal of all streams is to reach base level, the lowest level to which a stream can erode its bed.

Factors Controlling Stream Behavior

• Gradient is the ratio of drop in a stream per unit distance (slope); High gradient = Steep, Low gradient = Slow flow.
• Cross-Sectional Area
• Velocity
• Discharge is the volume of water transported by a river in a certain amount of time and can be calculated with Q = A X V

Flooding

• A flood is the rising of a body of water and its overflowing onto normally dry land due to rainfall, ice jams, snow melt, landslides, or dam failure.
• A floodplain is a flat area made of sediment deposited during floods.
• Upstream flood, “Flash Flood”, rises quickly and falls quickly.
• Downstream Flood rises slowly and falls slowly.

Flood Prediction

• Predict flood likelihood for an area in a given year or predict what area will become inundated.
• Flood frequency can be predicted for streams with large data sets using discharge data and topographic info to construct flood hazard maps.
• Watershed / Drainage Basin is an area where the surface runoff from precipitation onto the land flows together toward lower areas such as lakes or oceans.
• Stream Order is the method of classifying the size of a stream and its basin.

Explore the composition of the geosphere, focusing on elements and minerals. Learn about abundant elements like oxygen and silicon, and the characteristics that define a mineral. Understand the building blocks of our planet.