1. Wed. April 2 Do Now
What is your favorite topic that we have studied so far this semester and why?

2. Learning Intentions
Use relative dating to sequence events recorded in a rock formation.
Learn about how the Earth’s interior shapes Earth’s surface.
Apply basic science concepts like density, viscosity, convection, and energy transformation to Earth science.
Learn about the theory of plate tectonics and be about to explain evidence that supports this theory.
Learn about the three main kinds of plate boundaries: convergent, divergent, and transform.
Learn the causes & effects of earthquakes & where they occur.
Learn about the role of seismic waves in understanding Earth’s interior.
Learn about the scales that are used to rate the magnitude of an earthquake.
Find the epicenter of an earthquake using seismic data.
Learn how to keep safe during an earthquake.

3. Understanding Earth
Geology is the study of rocks and materials that make up Earth and the processes that shape it.
In 1666, Nicholas Steno ( ) noticed that shark’s teeth resembled mysterious stones called “tonguestones” that were found in local rocks.

4. What happened here and in what order?
Understanding Earth
Steno’s explanation helped him develop ideas about how rocks and fossils form.
These ideas are used in a technique called relative dating.
Relative dating is a way to put events in the order in which they happened.
What happened here and in what order?

5. Understanding Earth
The approximate age of each layer of a rock formation can be determined by applying Steno’s idea called superposition.
A stack of newspapers illustrates superposition.
Superposition means that the bottom layers of rock are older than the layers on the top.

6. Understanding Earth
Original horizontality states that sediment particles fall to the bottom of a basin, such as a riverbed, in response to gravity and result in horizontal layers.

7. Understanding Earth
Lateral continuity is the idea that layers of sediment extend in all directions when they form and before they become rock layers.
The idea of lateral continuity states that layers of rock are continuous unless a geologic event like a river interrupts the layers or an earthquake them.

8. Understanding Earth
Another important idea, developed by Scottish geologist James Hutton ( ), is that the "present explains the past."
The idea of cross- cutting relationships states that a vein of rock is younger than the rock that surrounds a vein.
vein

9. Sometimes rock pieces called inclusions are contained in another rock.
During the formation of a rock with inclusions, sediments or melted rock surrounded the inclusion and then solidified.
So, the inclusions are older than the surrounding rock.

10. Over geologic history, many animals and plants have lived and become extinct.
Their remains have become fossils.
The idea of faunal succession states that fossils can be used to identify the relative age of layers of a rock formation.

11. Calculating Earth's Age
William Thompson Kelvin ( ), who also proposed the absolute temperature scale that came to be named after him, meticulously calculated Earth’s age at 10 million and 100 million years.
His calculation was not accurate because he did not realize that Earth has internal heat from the core and radioactive decay.
Calculating Earth's Age

12. Calculating Earth's Age
Earth’s age was estimated by measuring the radioactive decay of uranium to lead.
With improved techniques and evidence from tree rings and glaciers, the age of Earth is estimated to be about 4.6 billion years.
Calculating Earth's Age

15. The Layers of the Earth
Earth’s surface is covered with a thin crust.
There are two kinds of crust:
continental
oceanic

17. Convection inside Earth
The rocky material of the mantle moves in very slow convection currents.
This movement is related to density & temperature differences in the mantle.
Hot material is less dense and rises.
Cold material is denser and sinks.

19. Do Skill Sheet 28-A Relative Dating