This Assessment will cover all 8 th grade EARTH AND SPACE SCIENCE STANDARDS
8ESS 1.0 The composition and properties of Earth’s interior are identified by the behavior of seismic waves.
1.1 The refraction and reflection of seismic waves as they move through one type of material to another is used to differentiate the layers of Earth’s interior.
1.2 Earth has an inner and outer core, an upper and lower mantle, and a crust.
1.3 The formation of the planet generated heat from gravitational energy and the decay of radioactive elements, which are still present today.
1.4 Heat released from Earth’s core drives convection currents throughout the mantle and the crust.
8ESS 2.0 Earth’s crust consists of major and minor tectonic plates that move relative to each other.
2.1 Historical data and observations such as fossil distribution, paleomagnetism, continental drift and sea-floor spreading contributed to the theory of plate tectonics.
2.2 The rigid tectonic plates move with the molten rock and magma beneath them in the upper mantle.
2.3 Convection currents in the crust and upper mantle cause the movement of the plates.
2.4 The energy that forms convection currents comes from deep within the Earth.
2.5 There are three main types of plate boundaries: divergent, convergent and transform.
2.6 Each type of boundary results in specific motion and causes events (such as earthquakes or volcanic activity) or features (such as mountains or trenches) that are indicative of the type of boundary.
8ESS 3.0 A combination of constructive and destructive geologic processes formed Earth’s surface.
3.1 Earth’s surface is formed from a variety of different geologic processes, including but not limited to plate tectonics.
8ESS 4.0 Evidence of the dynamic changes of Earth’s surface through time is found in the geologic record.
4.1 Earth is approximately 4.6 billion years old.
4.2 Earth history is based on observations of the geologic record and the understanding that processes observed at present day are similar to those that occurred in the past
(uniformitarianism).
4.3 There are different methods to determine relative and absolute age of some rock layers in the geologic record.
4.4 Within a sequence of undisturbed sedimentary rocks, the oldest rocks are at the bottom
(superposition).
4.5 The geologic record can help identify past environmental and climate conditions.

Earth Systems: Hydrosphere - all water on Earth, Geosphere - all rocks on and inside Earth,
Atmosphere - blanket of air surrounds the Earth, Biosphere - all plants and animals on Earth
2 main energy sources that drive the earth system = heat from the sun and heat flowing out of earth’s interior as it cools (convection currents)
constructive force = forces that build up mountains and other land masses; volcanoes, earthquakes and mountains
destructive force = forces that destroy and wear away landmasses; erosion and weathering
Layers of Earth: We know this by direct evidence (drilling rock samples) and indirect evidence
(seismic waves from earthquakes)
Order of layers of Earth: (from surface to center)Lithosphere (crust and upper mantle),
Asthenosphere (solid rock that flows), Mesosphere (lower mantle), Outer Core, Inner Core
Crust: tectonic plates here; solid made mostly of oxygen and silicon (oceanic basalt; continental granite)
Mantle: convection currents occurs here; very hot rock but solid; made mostly of magnesium and iron (3 parts: lithosphere, asthenosphere & mesosphere)
Outer Core: liquid metal; made of iron and nickel; movements here create Earth’s magnetic field
Inner Core: solid metal; made of iron and nickel
The two sources of thermal energy in Earth’s interior are gravity and radioactive decay.
How Scientists Differentiate the layers of the Earth:
 Direct evidence of earth’s interior = drilling samples
 Indirect evidence of earth’s interior = refraction and reflection of seismic waves (speed and path of the wave changes as it travels through different materials)
Convection Currents – heat energy from deep inside the Earth causes these to form; warm rock is less dense and rises; cool rock is more dense and sinks; in the asthenosphere cause tectonic plates (lithosphere) to move together forming a supercontinent called Pangaea
3 types of heat transfer:
conduction – direct contact of 2 objects touching each other
convection - circulation of a fluid (warm rises, cool sinks)
radiation – transfer of heat through electromagnetic waves
Earth is approximately 4.6 billion years old
Pangaea: when all the continents were connected as a single landmass
Evidence of Pangaea and Alfred Wegner’s theory of continental drift - continents fit together like puzzle pieces, fossils of same organisms matched in different continents, same rocks and minerals that match up including coal field deposits, and climate evidence (evidence that continents use to be closer to the poles or colder climates but are now closer to the equator and vice versa…glacial marks)

Process of Sea-Floor Spreading – based evidence gathered by sonar of the ocean floor
 Mid-ocean ridges are long chains of underwater mountains where magma continually rises to create new ocean floor
 Rock near a mid-ocean ridge is warmer, less dense and younger
 Evidence = ocean materials (pillow lava), magnetic striping (reversals) that are the same distance between the mid-ocean ridge and ocean floor band on each side, drilling samples (younger rock found near ridge – older found farther away from ridge)
Process of Subduction – when older, cooler and more dense rock (oceanic) is recycled back into the mantle when it collides with another plate (continental); pulled down by gravity
 Deep ocean trench – location where subduction occurs
Theory of Plate Tectonics: – the lithosphere is broken into 7 major and 7 minor tectonic plates that have moved over time and continue to move slowly at a constant rate
Tectonic plate movement occurs because of convection currents in the mantle.
Ring of Fire - place where earthquakes and volcanoes happen frequently, surrounds the Pacific plate
Types of Boundaries:
Convergent: 2 plates collide… see compression and types of landforms can create
Divergent: 2 plates pull apart… see tension and types of landforms can create
Transform: 2 plates slide past each other in opposite directions… see shearing
Types of Stress:
Compression –force that squeezes rocks until they fold or break; occur at convergent boundary; can cause folded mountains (C & C), subduction (C & O, O & O)
Tension – force that pulls on rocks and thins in the middle; occurs at divergent boundary ; can cause rift valley (C & O) or sea floor spreading (O & O) at mid-ocean ridge,
Shearing –stress that pushes a rock in 2 opposite directions; occurs at a transform boundary; can cause; earthquakes, ex. San Andreas fault in California (NA & Pacific plates)
Types of Faults:
Normal: hanging wall moves downward; occurs with tension force at a divergent boundary
Reverse: hanging wall moves upward; occurs with compression at a convergent boundary
Strike-Slip: two blocks slip past each other in opposite directions; occurs with shearing at a transform boundary normal reverse strike slip

Landforms:
Folded mountains: Appalachians, Himalayans, Alps; caused by compression forces ; consist of anticlines (upward arches) and synclines (downward arches)
Fault block mountains: Rocky & Sierra Nevada Mountains; caused by tension forces that result in a normal fault when the hanging wall slips down between 2 footwalls
Plateau: a large area of land elevated high above sea level caused by uplift forces
Earthquakes caused by force of plate movement; mostly happen near plate boundaries, transform boundaries, shearing stress,
seismic waves – vibrations that are similar to sound waves that travel through Earth carrying energy released by an earthquake
focus – area beneath Earth’s surface where rock that was under stress begins to break or ove
epicenter – the point directly above the focus
P-waves – primary – fastest, get their first, compress and expand ground like an accordion
S – waves – secondary – can’t move through liquids, vibrate at an angle of 90
Surface waves – get their last, creates circular motion of ground, causes most damage
seismograph – instrument used to record & measure earthquake’s seismic waves; the farther the seismograph station is to the epicenter the fewer waves it will record because part of Earth’s interior bends some waves and different materials in Earth reflect some of the waves
Scales used to measure earthquakes– Modified Mercalli, Richter & Moment Magnitude tell geologists how much energy was released by earthquakes
From past seismographic data, geologists have created maps of where earthquakes occur around the world. The maps show that earthquakes often occur along plate boundaries.
Volcanoes & Volcanic belts form along the boundaries of Earth’s plates near subduction zones.
(Ring of Fire, island arc)
A volcano forms above a hot spot when magma erupts through the crust and reaches the surface.
Fossils - mostly in sedimentary rock, Intrusions - igneous rock (can be radiometric dated)
Be able to identify examples of different types of fossils – molds, casts, petrified, carbon films and trace.
Relative age – this rock layer is older than that one and younger than this one.
Superposition - if rocks have not been disturbed, oldest rocks on bottom, youngest on top
Law of cross cutting - intrusions are younger than what they cut across (can't cut PB & Jelly until have PB & J)
Index fossil – only found in one time period but can be found in many locations
Geologic Column – record of all the layers of Earth in an area since time began
Intrusion – magma comes up from ground to form layer, causes contact metamorphism (melts sedimentary rock where it touches)
Extrusion – lava forms a layer of igneous rock
Unconformity - gap in geologic record where erosion or non-deposition occurred; symbolized by a wavy line in a geologic column

Radioactive(metric) dating - used to measure ABSOLUTE age – the atoms of one element
(unstable = isotope) break down to form another (stable) element; Carbon 14 changes to
Nitrogen 14 - good for dating things that were once living like bones, cloth, teeth, up to 50,000 years or igneous rocks Potassium & Uranium - long half life - good for rocks or older fossils
Half-life – time it takes for half of the radioactive parent isotope to decay into the stable daughter isotope… know how to calculate this!
Geologic Time Scale - a record of the geological events and the evolution of life forms as shown in the fossil record; used to show Earth’s history and can help identify past environmental and climate conditions
Earth’s history is based on observations of the geologic time record and the theory of
uniformitarianism which states that processes that occur in the present are similar to those that occurred in the past.
Pre-Cambrian Time – Earth forms 4.6 billion years ago, oceans, rocks, single cell organisms only
Paleozoic Era
Cambrian – first sea invertebrates, brachiopods, trilobites
Ordovician – first jawless fish, first insects
Silurian – first land plants
Devonian – Age of Fishes, amphibians
Carboniferous (Pennsylvanian & Mississippi)- swamps, ferns, reptiles
Permian – larger reptiles, Pangea forms, mass extinction
Mesozoic Era – Age of Reptiles
Triassic – first dinosaurs
Jurassic – large land dinosaurs
Cretaceous – T-Rex, birds, first flowering plants
Cenozoic Era – Age of Mammals
Paleogene – mammals, grasses
Neogene – large mammals and birds
Quaternary – Ice Age, Humans appear
Be able to identify the era and/or period of modern man (Quaternary Period in Cenozoic Era)