Cake Batter Lava
	Purpose  To understand some of the geological processes and the structures that form as lava flows across planetary landscapes by using cake batter as an analog for lava.
Key Words   lava flows  channels and levees  pressure ridges      Materials   cake batter  large mixing bowl, preferably with handle and pouring spout  wire whisk  large spatula  large baking sheet or wooden drawing board with a 10-cm grid on it  protractor with plumb line  stopwatch  "DataTables"  tape measure or ruler	Procedure 1. Stir the mixture of dry cake mix and water in the bowl. A few lumps are acceptable.   2. Prop up one end of the board at an angle of about 15° (use the protractor and plumb line to determine the angle). Make sure the board does not sag.   3. Hold the bowl of cake batter about 10 cm down-slope from the high end of the board. This will help prevent batter from spilling accidently onto the floor. Keep the bucket about 10 cm above the board. Pour the batter slowly. It is important to keep the pour rate as constant as possible.  Start the stopwatch when the flow front passes the zero line.   4. Watch the flow as it goes downhill and spreads out, and record the time it reaches each 10 cm mark. How far behind the flow front does the distinct channel become apparent?  5. Record the time when you stopped pouring (the flow will continue to move). Fill in the "Data Tables."   6. Note the channel and levees as well as shear zones within the levees. Does the channel extend the entire length of the flow?

 

7.

Using the tape measure, measure the length, width, and center depth of the flow and the channel width at each 10 cm mark. Fill in the "Data Tables."

 

8.

Draw the outline of the flow using the grid as a guide.

 

9.

When you are finished studying the flow, use the spatula to scrape the batter back into the bowl. The board should be clean and ready for the next procedure.

 

10.

Now prop the board up higher to an angle of about 25° and repeat the experiment. The batter may flow off the end of the board this time, so make sure the flat underlying surface is washable or protected with plastic. How do the flow structures in this flat part compare to those on the slope?

 

11.

Repeat all the measurements and fill in the "Data Tables."

12.

How do the two experimental flows compare? Is the ratio of channel width to flow width the same?

 

This activity has been copied, with permission, from the University of Hawaii's School of Ocean & Earth Science & Technology server to ours, to allow faster access from our Web site. We encourage you to explore the original site.

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