Wednesday, 2/17

Wednesday, 2/17

Agenda

• Bell Ringer

• Lesson - Plate Tectonics

• Vocabulary Quizizz

• Exit Ticket

Multiple Choice

True or false: all seven of Earth's continents used to be connected.

• True

• False

Part 1: Continental Drift

• In a 1912 lecture, meteorologist Alfred Wegener proposed the idea of continental drift.

• His idea came from 2 observations: 1. The continents seem to fit together like a puzzle. 2. Fossils of animals found on coasts of different continents also matched

• The original land mass he referred to as ‘Pangea,’ meaning ‘all land.’

Ideas Supporting Wegener

• Puzzle pieces: the way the continents fit together

• Fossil records: Locations of fossils on continents that would have fit together

• Geologic records: nearly identical rock layers on continents that would have fit together

Wegener Gets Denied

• Alfred Wegener had a major hole in his theory… He could not explain how, why, or when this occurred.

• Wegener’s idea was rejected by the scientific community and would not be revisited until after his death.

Part 2: Seafloor Spreading

• During the 1940s and 1950s, there were huge advances in technology.

• Scientists began bouncing sound waves off the ocean floor in an effort to make a map of the ocean floor.

• This led to a major discovery! In the middle of oceans around the world was a chain of mountains and rift valleys. These are now referred to as ‘mid-ocean ridges.’

• Where did these ridges come from?

Seafloor Spreading

• In the early 1960s proposed his now famous theory of “Seafloor Spreading.”

• Hess proposed that less dense magma, from beneath the Earth’s crust, was pushed upward through the denser ocean floor.

• The seafloor then was forced outward from the opening, spreading the seafloor apart.

Ideas Supporting Hess

• In 1968, scientists collected rocks from the ocean floor, and also drilled samples from different distances between the ridge and the coastline.

• They found that the youngest rocks are found along the mid-ocean ridge, and became increasingly older as you move outward toward the coastline.

• These findings supported both Hess’s theory of seafloor spreading, and Wegener’s theory of continental drift.

Independent Activity

• Click on the Quizizz link in the chat box.

• Complete the Quizizz game to review vocabulary.

Exit Ticket

• Please complete the Exit Ticket in Canvas

• When you are finished, you are free to go.

• Have a great rest of your day!