Question

Name Date CONCEPTUAL Physical ScienceIEE SHEE Gs Chapter 21: Plate Tectonice and Earth's Inter Sea-Floor Spreading The rate of sea-floor spreading between two points on the ocean foor, we can determine the rate of spreading. Diagrams A, b, show stages of sea-floor spreading. Spreading begins at A, continues to B where rocks at centimeters per year. If we know the distance and age o s locationP begin to spread to the farther-apart positions we s ㈜isdated at 10 milion years. Using the scale: 1 mm-50km, use a rer to see at C. At C newer rock at the ocean crest 1. separation rate of the two continental landmasses in the past 10 million years, in cmyr 2. age of the sea floor at P in Diagram C (1 cmlyr 10 km/million years) Sea level - 143

Answer 1

Distance between mid-oceanic ridge and point S = 3mm = 150 km

No. of years taken = 10 million years

1. Separation rate for two landmasses for the last 10 million years = 1.5 cm/year.

2. Distance between point P and mid-oceanic ridge = 30mm = 1500 km

Age of the rock = 1500/10 = 150 million years