How To Measure Seafloor Spreading Rates in the Classroom

In this blog, learn about an activity that allows high school age students to use real data from previous JOIDES Resolution research expeditions to compare the spreading rates in different areas of the seafloor and find out how fast is “superfast.”
 
To understand the research the Superfast Spreading Rate Crust 4 scientists are currently conducting requires an understanding of seafloor spreading. Seafloor spreading is mainly the result of convection currents dragging the ocean plate along with them, but that is not the only force pushing (or pulling) the seafloor, nor does it necessarily occur at a constant rate. There is a great range of factors and forces affecting the direction and rate of seafloor spreading (to get an idea of the variability read this blog).
 
Another way students can get an idea of the variability of seafloor spreading is through the “The Race Is On…With Sea Floor Spreading!” activity from the Deep Earth Academy. This activity for high school students uses real data from previous JOIDES Resolution research expeditions, including expeditions that have drilled hole 1256, the same hole the JOIDES Resolution is drilling right now. The data is presented on a map that shows different ages of seafloor in this part of the Pacific (the map in the activity is almost identical to the one in the scientific prospectus for our current expedition). The students use the map to measure and calculate the spreading rates at different locations. The activity is presented in a very straightforward lesson plan that includes everything an educator would need to successfully facilitate this activity.
 

For another, more introductory, activity about seafloor spreading that also makes use of real ocean drilling data, read this blog

Comments

Testing

What kind of tests do you conduct for sea floor spreading?-M.G.

The rock samples can be

The rock samples can be radiometrically dated to determine how long ago they were formed. By comparing the date they were formed with the formation dates of other rocks on the same ocean plate, you can figure out average spreading rates. For an over-simplified example, if one rock was found to be formed 6 million years ago and another rock 1 kilometer way was formed 5,900,000 years ago, then the average spreading rate between those two rocks would be 1 kilometer per 100,000 years which can also reduced to 1 centimeter per year (1 kilometer=100,000 centimeters).

question

do you think that there will eventually be more technically advanced method to check the rate of sea floor spreading? - the botts(:

In the last couple decades,

In the last couple decades, scientists have been able to use GPS and satellites to directly measure the spreading rates of seafloors year to year. For more ancient spreading rates, though, they still need to drill up cores from the ocean crust and radiometrically date the rock samples to determine the rates.

Sea Floor Spreading

Hi. What is the oldest peice of magnectic stripe/rock you have found and where did you find it? Please reply!
Sarah H.

The oldest ocean crust was

The oldest ocean crust was drilled in the northwest Pacific ocean and the rocks were about 170 million years olds. Even older continental rocks that were mixed in with the ocean rocks have been found through drilling off the coasts of the Falkland Islands and Australia. These rocks are over 550 million years old.

In class we learned that you

In class we learned that you can tell how old the rocks are. I learned that you can tell from the ooze,( dead plankton EWWW) how close you are to the mid-ocean ridge, and a special machine that records the pattern of the rocks...etc., Were you always excited to learn more about this? Do you really believe in Pangea the super continent? Please Reply! Thanks! -Iya A.

Being a scientist is always

Being a scientist is always exciting because you are always exploring and discovering and learning new things. For the answer to your Pangaea question, read the response to the "Pangea" comment below.

Sea Floor Spreading

What is the rate of sea floor spreading? Reply!
Sarah H.

It varies depending where on

It varies depending where on Earth and when in time you are measuring, but most seafloors spread at rates of less than 8 cm per year.

Pangea

Hi. I was wondering if you belive in the theory of Pangea and why. I really want to know! :)
Sarah H.

Great question! Scientists do

Great question! Scientists do not think of things in terms of belief but whether there is enough evidence that can be observed with our senses that shows that something has occurred (or continues to occur, or will occur in the future). There is a lot evidence of that, through plate tectonics, all the continents have come together at various points in Earth's history to form supercontinents such as Pangaea. Pangaea was the latest supercontinent on Earth, and was here about 250 million years ago. Some of the evidence for Pangaea are the continents that fit together like puzzle pieces (like Africa and South America) have the exact same ancient fossils on both coasts, despite the fact that, today, these continents have completely different plant and animals from each other inhabiting them. More evidence is there are mountains that were formed at the same time as Pangaea and made of the exact same rock types that are now on continents far away but that also fit together perfectly like a puzzle (we now know that the Appalachian Mountains are the same mountain chain as the Caledonian Mountains in Greenland, Scotland and northern Europe). Further we know that seafloors are spreading and also moving continents as they do so. Scientists have been able to measure with satellites that the Atlantic Ocean floor continues to spread and move Africa and Europe farther away from the Americas and know this has been happening for about 170 million years, enough time to move them as far away from being joined in Pangaea as they currently are. We also know places here on Earth where a continent is breaking apart and may one day be an ocean, such as the Great Rift Valley in Africa. That's a little bit of the evidence, but if you do more research you will find out about a lot more evidence that scientists have discovered that show that Pangaea did once exist.

Pangea??

Is Pangea real? Do you think you would've believed Mr. Alfred W. if you had the opportunity to witness his discovery? Thanks!-Iya A.

All the evidence points to

All the evidence points to Pangaea, when all the continents came together as a supercontinent millions of years ago, being a real place. When Alfred Wegener first suggested the idea, it probably would have been hard to believe since we had no idea how the continents could move, but now we know the continents move because of plate tectonics and seafloor spreading and have even been able to observe them slowing moving over the past few years, so that was a brilliant insight on the part of Mr. Wegener.

I have learned what sea-floor

I have learned what sea-floor spreading is but how can you tell the rate by rock samples? Also how many samples do you guys plan on collecting?-Bain

The rock samples can be

The rock samples can be radiometrically dated to determine how long ago they were formed. By comparing the date they were formed with the formation dates of other rocks on the same ocean plate, you can figure out average spreading rates. For an over-simplified example, if one rock was found to be formed 6 million years ago and another rock 1 kilometer way was formed 5,900,000 years ago, then the average spreading rate between those two rocks would be 1 kilometer per 100,000 years which can also reduced to 1 centimeter per year (1 kilometer=100,000 centimeters). This expedition is hoping to drill the hole a couple hundred meters deeper into the crust and bring up as many core samples as they can from that.