Earth Systems

The Earth’s resources were determined when the planet formed. Earth is ~4.6 Billion years old Almost all of the elements currently found on the planet were present during formation. As the forming Earth cooled, heavier elements condensed due to gravity and settled based on mass. Ex. Iron sank towards the center and silica settled towards the surface. Gaseous elements became the atmosphere

The Earth’s Layers This settling by mass resulted in distinct vertical layers Core - the innermost zone of the planet made of nickel and iron. Mantle - above the core containing magma Crust - the outermost layer of the planet.

The Earth’s Layers Asthenosphere- the outer part of the mantle, composed of semi- molten rock. Lithosphere- the brittle outermost layer of the planet

Lithosphere Made up of several large plates and numerous small plates Includes the upper mantle and crust Contains soil on the upper crust which is what allows life on the planet to exist because they contain the elements required for life

Earth is dynamic and constantly changing Earth’s geologic cycle consists of 3 major processes: Tectonic Cycle Rock Cycle Soil formation

Convection and Hot Spots Despite being 4.6 byo, the planet remains very hot at its center The heat causes hot magma plumes to well upward from the mantle producing hot spots Hot Spots: places where molten material from the mantle reaches the lithosphere

Theory of Plate Tectonics States that the Earth’s lithosphere is divided into plates, most of which are constantly in motion Tectonic Cycle – The sum of the processes that build up and break down the lithosphere

Plate Tectonics The lithosphere is broken into plates: Oceanic Plates: Lie primarily beneath oceans Crust is dense and rich in iron Continental Plates: Lie beneath land masses less dense and has more silicon dioxide Continental plates are lighter and will rise above oceanic plates

Plate Tectonics Convection: the movement of hotter and less dense material to rise, and colder, denser material to sink which results in the transfer of heat. Where oceanic and continental plates come together, subduction occurs Subduction: Plates passing under one another

Consequences of Plate Movement As a plate moves over a geologic hot spot, heat from the rising mantle plume melts the crust and forms a volcano Volcano: a vent in the Earth’s surface that emits ash, gases, and molten lava.

Plate movement over a hot spot Hawaiian islands are an example of how land can form over hot spots due to volcanic eruption Geologically, this is how all land originally formed The eruption and cooling of molten lava

Types of Plate Contact Divergent plate boundaries- when plates move apart from one another. Convergent plate boundaries- when plates move toward one another and collide. Transform fault boundaries- then plates move sideways past each other.

Divergent Boundaries Occur between oceanic plates Plates move away from each other, new magma rises and cools to form new lithosphere This is called seafloor spreading

Convergent Boundaries If oceanic collide with continental, a coastal mountain range will form because the lighter continental plate will rise on top of the heavier oceanic plate which will subduct If 2 continental plates collide, both margins will rise forming a mid-continental mountain range

Transform Fault Boundaries Transform boundaries are where plates slide against each other Faults- a fracture in rock across which there is movement. Earthquakes- occur when the rocks of the lithosphere rupture unexpectedly along a fault.

The Rock Cycle Rock cycle- the constant formation and destruction of rock.

The Rock Cycle Igneous rocks- rocks that form directly from magma. Sedimentary rocks- form when sediment such as mud, sands, or gravels are compressed by overlying sediments. Metamorphic rocks- form when sedimentary, igneous or other metamorphic rocks are subjected to high temperatures and pressures.

Weathering and Erosion Weathering- when rocks are exposed to air, water, certain chemicals or biological agents that degrade the rock.

Weathering and Erosion Physical weathering- the mechanical breakdown of rocks and minerals. Chemical weathering- the breakdown of rocks and minerals by chemical reactions.

Erosion Erosion- the physical removal of rock fragments from a landscape or ecosystem. Wind, water, ice transport and living organisms can erode materials. Deposition- the accumulation or depositing of eroded material such as sediment, rock fragments or soil.

Soil Soil is important because it Is a medium for plant growth Serves as a filter for water A habitat for living organisms Serves as a filter for pollutants

The Formation of Soil Factors that determine the formation of soil: Parent material- what the soil is made of influences soil formation Climate- what type of climate influences soil formation Topography- the surface and slope can influence soil formation Organisms- plants and animals can have an effect on soil formation Time- the amount of time a soil has spent developing can determine soil properties.

The Formation of Soil Parent Material- the rock material from which soil is derived.

Soil Horizons As soils form, they develop characteristics layers.

Soil Horizons O horizon- (organic layer) composed of the leaves, needles, twigs and animal bodies on the surface. A horizon- (topsoil) the zone of organic material and minerals mixed together. B horizon- (subsoil) composed primarily of mineral material with very little organic matter C horizon- (parent material) the least weathered horizon and is similar to the parent material.

Physical Properties of Soil Texture- the percentage of sand, silt and clay the soil contains.

Physical Properties of Soil Porosity- how quickly the soil drains (which depends on its texture)