Slow Motion Earth

• How do we know slow objects are moving?

• Plates– Broken pieces of

Earth’s crust

• Theory of Plate Tectonics – Earth’s plates move

ever so slowly in all directions

Calculating Distance

• If the pacific plate moves 5 cm a year, how far will it move in 1,000 years?– 5 cm x 1000 yr = 5000 cm which is 50 m

• What would this convert to per day?– 5 cm ÷ 365 days = .0137 cm/day

Predicting

• Los Angeles is on the Pacific Plate moving northwest. San Francisco is on the North American Plate moving southeast. These 2 cities are moving toward each other at 5 cm/yr. If the two cities are 554,000 m apart, how long will it take the two cities to meet?

• 554,000 m x 100 cm/m = 55,400,000 cm• Time = 55,400,000 ÷ 5cm/yr =• 11,080,000 years