# Estimating the spreading rate of Atlantic and Pacific ridges

#### Summary

Given maps of bathymetry of Atlantic and Pacific Ocean, students estimate spreading rate of each ridge writing a matlab script that plots a line of bathymetry, and calculated bathymetry as a function of spreading rate. They then vary the estimated spreading rate manually until they produce a bathymetric curve that closely resembles the real bathymetry.

## Context

#### Audience

upper level undergrad/ graduate level course in tectonics/geodynamics

#### Skills and concepts that students must have mastered

familiarity with matlab

high-school math

isostacy/subsidence

density

high-school math

isostacy/subsidence

density

#### How the activity is situated in the course

stand-alone exercise

## Goals

#### Content/concepts goals for this activity

understand why ocean bathymetry varies in a systematic way

appreciate how spreading velocity controls bathymetry of ocean

appreciate how spreading velocity controls bathymetry of ocean

#### Higher order thinking skills goals for this activity

transforming mathematical equation into matlab script

appreciate that "all models are wrong, but some models are useful" i.e., the modeled bathymetry does not perfectly match the real bathymetry, but can capture the general subsidence pattern.

appreciate that "all models are wrong, but some models are useful" i.e., the modeled bathymetry does not perfectly match the real bathymetry, but can capture the general subsidence pattern.

#### Other skills goals for this activity

writing equations in matlab

plotting data in matlab

plotting data in matlab

## Description and Teaching Materials

For this lab students are provided with a handout describing the concepts of subsidence of aging oceanic lithosphere and the equation relating ocean subsidence to age. They are then provided data files of bathymetry of the atlantic and pacific oceans.

Students then must write a script to plot the real data and the calculated bathymetry as a function of spreading velocity, and estimate the spreading velocity of each ocean by trial and error based on visual curve-matching.

data for "Estimating the spreading rate of Atlantic and Pacific ridges" ( 22kB Apr30 12)