Moving AlongHawaii gets built – and moves along

on the top of the Pacific Plate.

Which way is the Plate moving?

The Data

Oldest Youngest

MY MYHawaii 1 0Maui 1.3 0.4Molokai 1.8 1.3Oahu 3.3 1.9Kauai 5.6 4.5

How to Average• Averaging is a math process. You add the

numbers, and divide by the number of numbers.• Example:

Hawaii 1my 0my• Add the numbers: 1 + 0 = 1• How many numbers were there?• 2• Divide the sum (1) by the number of

numbers (2): 1 / 2 = .5• Put in the units: .5 million years

• Now, do it for each of the islands.

• Make a column between the data on the worksheet – and title it “Average Age”

The Data

Oldest Youngest

MY MYHawaii 1 0Maui 1.3 0.4Molokai 1.8 1.3Oahu 3.3 1.9Kauai 5.6 4.5

Measuring the Map• On the map, place a dot or x where the

hotspot is now – Just to the left of the “L” in Loihi is a good guess.

• Place a mark in the middle of each island – Hawaii, Maui, Molokai, Oahu and Kauai

• Use a ruler to measure the distance from the Loihi hotspot to each island – use centimeters.

Measuring the Map II• Note that the scale is 3 centimeters equals 100

kilometers.• Scale size (cm)

Actual size (km)

• 3 cm Your measurement (cm)100 km Your measured (km)

• Cross Multiply: Multiply your measurement by 100 then Divide by 3.

• Enter that information on the chart.

=

Your chart might look something like this:

Oldest Youngest Average Distance

MY MY MY km

Hawaii 1 0 0.5 50

Maui 1.3 0.4 0.85 216

Molokai 1.8 1.3 1.55 283

Oahu 3.3 1.9 2.6 383

Kauai 5.6 4.5 5.05 533

How to Graph

• Look at the axis on the graph on the worksheet

• Average Age is the Horizontal (x) axis

• Distance from the Hotspot is the Vertical (y) axis

• Look at the Units: (x) millions of years and (y) hundreds of kilometers

• Your data on the table should already be close to ready for this

How to Graph II

• For Hawaii – your information is something like - .5 million years & 50 km

• On the horizontal axis – go right .5• Now go up to 50 km (.5 hundred)• Put a dot.

• For each island, do the similar process – Horizontal for Age – Vertical for Distance

How to Graph III

• You can connect the dots – and in some graphs, that’s what you want to do. For this graph we want to find the

Best Fit Linesometimes called the regression line by statistics fans

• (if you do this whole process by spreadsheet – you can have it do the graph and regression line!!!)

How to Graph IV

• Best fit line – Read and/or think carefully – is the origin (0,0) part of the line? For this chart, yes, the hotspot is at 0 kilometers and 0 age.

• Draw a straight line – including 0,0 – that passes through as many of the points as possible. IF you can’t make it go through points, it has to give the idea of where the points are going. An equal number should be above and below the line.

This is one exampleMoving Along

y = 121.63x

0

100

200

300

400

500

600

700

0 1 2 3 4 5 6

Average Age - (million years)

Dis

tance

fro

m H

ot Spot (h

undre

d k

m)

Series1

Linear (Series1)

Movement of the Pacific Plate based on the Hawaii Hotspot

Now to Calculate the Rate of Motion

• Choose a distance – in this case, try 500km. Draw a straight line from the vertical axis (y) at 500 km over to your Best Fit Line.

• Now, from that point, draw a straight line directly down to the horizontal axis (x)

• What is that number?

Calculate the Rate of Motion II

• You now have 500 km and some other number of million years. Lets pretend it is 3 million years.

• We want to find the number of centimeters per year, so we need to convert kilometers to centimeters and million years to years.

• 500km = 500km x 1000 m/km x 100 cm/m = 50,000,000 cm

• 3 million years = 3,000,000 years

Calculate the Rate of Motion III• Last step –

• 50,000,000 cm 3,000,000 years

• Cancel some zeros –

• 50 cm = 3 years

• 16.6 cm/year

If we let Excel do it…

• 121.63 km / million years

• Equals 12163000 cm / million years

• Which divides out to 12.163 cm / year