Do the Math
Name:
The Hawaiian island chain consists of 4 large islands and several smaller ones. The big
island of Hawaii is still forming on its southeastern side. The island is still growing
because of a hot spot in the mantle. A hot spot is where molten rock material breaks
through the crustal plate and begins as an underwater mountain. If the crustal plate moves
slowly then the underwater mountain will eventually form an island. In this activity,
students will be asked to convert km to cm. Then, using scientific notation, students will
divide two large numbers to calculate the speed of the crustal plate.
Figure 8.7 Below is a table showing the distance between two Hawaiian Islands in kilometers.
Without using a calculator, convert the distance between the two islands from kilometers
to centimeters. To calculate the approximate speed of the crustal plate use the following
speed formula:
Speed = distance/time
Without using a calculator, calculate the speed of the crustal
plate for the three pairs of islands in the table. Once you have completely filled in the
table below, do the calculations to find the average speed of crustal movement of all four
pairs of islands.
Two Hawaiian
Islands
Distance
between two
Hawaiian
Islands (km)
Distance
between two
Hawaiian
Islands (cm)
Difference in
Age of the
islands (years)
Approximate
speed of the
crust between
the times that
the two islands
formed
(cm/year)
Kauai – Oahu
170
17,000,000
1,500,000
11.3
Ohu – Molokai
110
1,000,000
Molokai Maui
80
300,000
Maui - Hawaii
150
1,200,000
1. What is the average speed of the crustal plate over the past 5,100,000 years?
2. Would you describe the movement of the crustal plate as consistent or
fluctuating? Describe your answer in detail.