APES UNIT 4

APES UNIT 4: Earth Systems and Resources 

4.1 Plate Tectonics 

Vocabuarly: 

Tectonic Plates are slabs of rock or lithosphere floating on top of the mantle 

Mantle: Molten, magma sea that tectonic plates float atop 

Remember: The reason that the mantle is a liquid and NOT a solid is because of the heat given off of the Earth’s core.

Earrths Core: Dense ball of nicole, iron, and radioactive elements (which melts the mantle by decaying) 

Background: Plate Tectonic’s Movements or collsions or the boundaries that they form ultimately shape all of the landforms we have on Earth. Understanding the Following Plate Boundarys;

• Divergent Boundary: Plates move away from each other. Explained: Where plates are moving away from each other due to a particularly hot portion of the mantle where magma’s rising towards the surface and pushing them apart because this typically happens between two ocean plates, aka seafloor spreading. This is how we get mid Oceanic features like trenches and underwater ridges. 

• Convergent Boundary: Two plates COLIDE; Explained: It is more dense so the oceanic plate is going to be subducted or forced beneth the continental plate. (in simple terms one plate moves underneath the other) The subduction of the oceanic plate is going to force magma up through the lithosphere on the continental plate. This is going to lead to volcanic mountain ranges forming along the coast of this boundary  + form trenches. 

• Transform Boundary: Two plates slide past each other in opposite directions ; causes earthquakes; sometimes the plates get stucked or locked. They slide all at once releasing tons of  tension causing an earthquake! 

4.2 Soil formation and Erosion 

Defintion: Soil - a complex mixture of tiny particles of weathered rocks, such as sand, silt, and clay and has living material & organic material. It is also full of empty space aka pore space.  Pore space is so critical because it allows oxygen and water to fill the soil which allows plants roots to have access to these two things they need in order to grow

REMEMBER SOIL IS 3 factors - minerals, open spaces, and organic materials 

How Soil forms; The inorganic or mineral components of soil come from the weathering of rocks so what happens is over time the force of the rain and the freeze thaw cycle of of water breaks the rocks into smaller pisces. These small rocks come from PARENT MATERIAL. Soil is more than broken up pieces of rock - if we look at different layers or horizons we can the top layer is organic material which is called O horizon.

Layers (Most top to bottomn): 

O horizon - top layer filled with organic material 

A horizon - aka top soil, very crtical layer of the soil because it contains both organic matter and mineral components of soil, it contains nutrients like nitrogen and phosphorus as well as the water and oxygen in its pore spaces, all of which are crucial to supporting plant growth. 

B Horzion - subsoil, contains little organic material, holds essential nutrients 

C horizon - rocks of parent material that have undergone very little weathering since they are very deep 

Difference between weathering & erosion; 

Weathering is the breakdown of rocks into smaller & smaller pisces 

Erosion is the movement of those rock pieces by  the wind and the rain ( a natural process which can be worsned by human activity & can degrade soil) It can decrease the soils water  and removes nutrients for plant growth. The water in soil gives clean drinking water to some ground species & humans. 

Three different types of rock 

• Igneous - formed by COOLING and classified for their silka content (ex; granite)

• Metamorphic - formed by intense HEAT and pressure, high quartz content

• Sedimentary - formed by PILLING and cemendting of various material 

4.3 Soil Composition and Properties 

Factors/properties that affect a soils fertility or it’s ability to support plant growth

• Prop 1: Soil texture; percentage of sand, silt and clay that a soil is made up of. This is important bc these three particles have vastly different sizes which give the soils they make up vastly different characteristics.  

  • Sand is the BIGGEST particle by far followed by silt and then clay is the smallest. Bigger particles can’t pack as tightly together so particles of sand have much larger space or pores (empty space between soil particles) between them. So, a soil with more sand will have more pores, and those with larger pores will allow water to drain through the soil more easily. On the other a hand, a soil with more clay will have smaller pores and will not allow water to drain through as easily. 

  • Permeability: the ease/speed that water can drain through a soil

  • So a soil with larger pore space, that’s highly permeable, will have a low holding capacity (and vice versa!)

  • Holding capacity: ability of a soil to hold water 

  • If a soil isn’t permeable enough due to tightly paced clay particles with small pores, water will infiltrate really slowly. The soil will hold so much water that it can drown the plant by preventing the roots from accesing oxygen but if a soil is TOO permeable due to lots of sand and large pore space, then the water drains too quickly. The plants roots can have access to the water before it drains (low water holding capacity) So soils with a mixture of sand, silt, and clay equal to a medium pore size, medium water holding capacity.

• Prop 2: Soils have chemical properties like soil PH. 

Soil Ph: The measure of acidity of a soil. The lower the pH of a soil the more acidic and higher the H+ ion concentration. 

KEY TO KNOW: When soil PH goes down or when soil becomes more acidic it can be degraded in two key ways.

1. Acidic soils have lower nutrient levels. This is because at low pH levels or higher acidity the soil has a higher concentration of H+. These H+ ions leech nutrients like nitrogen or calcium out of the soil since plants need these nutrients in order to grow; this can stunt or stop their grow all together. 

2. Acidic soil can actually damage plants roots directly by making toxic metals like aluminum more soluble in the soi. In other words, at lower  pH levels this increases in H+ ion concentration allows naturally occurring aluminmum in the soil to dissolve more easily. This means that the aluminmum is more free to enter plants roots which damages them and limits their growth so we know soil PH is crticakl to determining to determining plant nutrient levels.

3. KEY REMEMBER: Nitrogen and phosphorus levels of soil are the two biggest limiting factors for plant growth. 

These factors and physical properties of soil determine the soils fertility or ability to support plant growth. EX: Factors such as more nutrients = more fertile, low ph or more acidic less fertile 

4.4 Earth’s atmosphere

• 78% of atmos. Is nitrogen (needs fixation to be avalible)

•  21% oxygen 

• 1% argon 

• 0,4 percent races gases

Layers of earths atmosphere; 

• Troposhere; The layer closest to earth is where weather occurs here and where the air we breathe comes from. Tropo = change 

• Stratosphere = second layer, saves us from the sun because of the dense concentration of ozone molecules in this layer that absorb the UVB and UVC rays that can mutate our DNA or cause cancer or cataracts 

• Mesophere  = middle most layer (starts with M) The gas molecuules are becoming less and less dense as we get further from Earth’s surface next

• Thermosphere = hottest layer, it receives the most direct solar radiation, this is also the region where the aora borealis aka the northern lights occur. This is because protons and electrons blown toward Earth by solar winds collide with nitrogen and oxygen 

• Exosphere = outermist layer and the space thats merging with oterpsace.