TIDES AND TURBIDITY FLOW: TWO LEARNING OBJECTS FOR TEACHING SEDIMENTOLOGY AND OCEANOGRAPHY

Learning objects are a way of thinking about learning content. Objects include simulations, interactive data sets, quizzes, surveys, annotated texts, and adaptive learning modules. They provide material for a unit, a discrete lesson, and/or a sub-lesson within a larger course. We have developed two learning objects for use in sedimentology classes, one that simulates tides in Long Island Sound and the Connecticut River (http://learningobjects.wesleyan.edu/projects/tides/index.html) and one that demonstrates turbidity current flow (http://learningobjects.wesleyan.edu/projects/turbiditycurrents/index.html).

Long Island Sound is a relatively shallow, restricted basin that experiences a maximum tidal range of about 10 feet. The tidal simulation uses NOAA data for October 2002. Every ten minutes the tidal heights are updated, as is the phase of the moon. Displaying bathymetry and towns is optional, and highest and lowest tides can be highlighted in bright colors. Before running this simulation, students can make predictions about tidal behavior, e.g. where and when will tides be the highest, and the tidal effect on the height of the Connecticut River, how long it will take a high or low tide to enter and exit Long Island Sound. A zoom feature allows close-up examination, of a particular area. Users have the option of looking at the tidal heights for the entire month from over 75 locations and displaying tidal height for a selected time for all of these same locations. After making these predictions, students can run the simulation to test their predictions and to see how tides actually flow in this basin and river.

The turbidity current simulations are QuickTime movies of whole milk (density of 1.032 gm/L at 10 deg C) being released into a 1.65 m long tank of water. The flow can be observed from several angles. Turbulence, the surge-like nature of this type of short-lived turbidity current and turbulent resuspension can be observed. The dimensions of the tank and time elapse of the flow are given. After observing the flow, students can apply various turbidity current equations for the velocity of the head and body. Both viewing and working with the calculations allow students to develop a better understanding of how turbidity currents move.