GEO-1030 Homework: Hawaiian hot spot age progression possible points: 10 NAME: __________ email: _______

This figure shows volcanic islands making up the Hawaiian chain. For 11 of the islands, ages are given in millions of years (e.g., Hawaii is the youngest at 0-0.4 m.y. and Midway is the oldest, at 27.7 my).

1. Complete the table below, providing an age and distance from the hot spot for each island.

Using the scale bar on the map, determine the distance in km of the 11 islands from the hotspot (large black dot) located at the southeastern shore of the island of Hawaii. Note: to determine distances, convert the edge of a sheet paper to a kilometer ruler, by marking a tic every 200 km using the scale bar; then split each interval in two to add 100-km tics. You should be able to measure distances to an accuracy of ±50 km with this kilometer ruler.

island: Hawaii Maui Molokai Oahu Kauai Nihoa Necker Gardner Laysan Pearl& Hermes Midway

age:

distance:

2. On the plot grid on the next page, plot distance (km) from the hotspot on the Y axis (vertical axis) versus island age (m.y.) on the X axis (horizontal axis) for the eleven islands. If an island has a single- number age (ex. 5.1), plot a point; if the island has an age range (ex. 2.6-3.7), plot a segment of horizontal line.

3. Draw a “best fit” line through your points – that is, anchor one end of your ruler at 0,0 and adjust the ruler so that approximately half of the points are above the ruler’s edge and the other half are below it.

4. Determine the slope of the line – that is, maximum distance divided by maximum age. This is the rate (in km/m.y. or mm/yr) at which the Pacific plate is moving roughly NW over the hotspot. 5. If basalts from French Frigate Shoal were dated with K-Ar, what would you predict their age would be based on your plot? _________ m.y.

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Age, my