Today, we began the second part of the Earth History unit with a focus away from fossils and into geology. A good portion of the material will already be again be familiar since we will review weathering (rock is broken apart into pieces of sediment by force or by chemical reaction/corrosion), erosion (wind or water picks up the sediment), and deposition (the sediment eventually gets dropped somewhere). Those are examples of slow changes to the Earth's surface.
We will cover that but go into more depth and mention glaciers too and how they have slowly but dramatically altered the surface.
Besides slow changes, we will cover rapid changes such as volcanoes, earthquakes, landslides, etc. Though it isn't a part of the standards, I am going to add the layers of the Earth since they too play a role on how the surface changes. I plan on going deeper to give my students a more thorough background and help prepare for the higher grades.
Example: I will mention the inner cores (plural since an inner-inner core has recently been discovered. Another example is that I will mention the lithosphere, which is actually much more accurate than "crust." The lithosphere indeed covered the solid outer crust but also the solid upper part of the mantle. It is actually the lithosphere that is broken up into individual pieces (tectonic plates) that float on the liquid part of the mantle.
It is important to note that the layers of the Earth aren't simply separated like you see in pictures. It isn't like you go from solid crust to liquid mantle as if crossing the line from North Carolina into South Carolina. The temperature gradually gets hotter the further down one goes and the state of matter (solid or liquid) gradually changes too.
The Standard(s) Covered: 4.E.2.3 Give examples of how the surface of the earth changes due to slow processes such as erosion and weathering, and rapid processes such as landslides, volcanic eruptions, and earthquakes.
Today's warm-up was a review of material throughout the year.
Afterwards, we reviewed the notes from the fossils section and then took notes for this section:
· The Earth is in a constant state of change. Some changes are fast while others are slow
· Change can happen in an instant or take millions of years
Weathering – the process of breaking down rock by wind or water (mechanical) or by acids and oxygen (chemical)
· A plant’s roots can also break down rock by expanding existing cracks.
Sediment – tiny particles of rock or soil
Erosion – the process in which sediment it picked up by wind or water
· Older mountains are rounder and smoother due to more erosion
· Younger mountains are more jagged due to less erosion
· It took the Colorado River millions of years to erode enough rock and soil to create what is now the Grand Canyon.
· Underground water can erode away soil and rock which can cause sinkholes to form.
Stalactite – an icicle-like structure hanging from the roof of a cave, formed of minerals deposited by dripping water.
A stalagmite is similar but points upward from the floor of a cave.
Deposition – the process in which sediment is dropped. This can make land more fertile.
Delta – a landform that forms from deposition of sediment carried by a river where the water slows down
Landslide – the usually rapid downward movement of a mass of rock, earth, or artificial fill on a slope
Earthquake – a sudden and violent shaking of the ground
Vibration – a series of small, fast movements back and forth or from side to side
Geologist – a scientist who studies the nonliving things that the Earth is made of, how they form, and how they change
Seismic Wave – a wave of energy that is generated by an earthquake or other vibration
Seismometer – a device used to measure the energy of an earthquake
Volcano – a vent, or opening, in Earth's surface through which molten rock, gases, and ash erupt.
· Volcanic activity creates new crust (rock) on the Earth’s surface
Crust – the outermost layer of the Earth that is solid
· Some crust is melted back into the mantle while new crust is made by lava from volcanoes
· The amount of crust stays the same
Tectonic Plate – individual, massive pieces of crust that float on the mantle
Fault – a crack in the Earth’s crust where neither side is held together, a boundary between tectonic plates
Mantle – the next layer that is made up of molten (melted) rock
Outer Core – below the mantle, it is made up of liquid metal
Inner Cores – the innermost layers of the Earth made of solid metal. It is very dense and is hotter than the outermost layer (corona) of the sun due to intense pressure
Lastly, the unit test is going to be on Friday, March 18th. I am working on a practice test to review and it will go live soon.