How Deep Can We Go?

Okay, so here we are, back at a scientific drill hole that's already pretty deep -- 1.5 kilometers below the seafloor, to be exact. And, if all goes well, before this 6-week expedition is over, we'll increase the depth of the hole by another 400 meters into the lower oceanic crust.

But some folks have asked us recently why we don't drill to the mantle -- or for that matter, Earth's core. Since we're already here, why not go all the way, right?

Well, as you can see from this drawing, the mantle and core are still a long way from where we sit here at the top of the ocean.


To begin with, there's more than 3,600 meters of water that lie between us and the seafloor -- and the point at which the Earth's upper crust begins. From there, we're going to try to extend Hole 1256D to a total of roughly 2 kilometers into the oceanic crust (the crust itself is 6 kilometers thick). If we're successful, the bottom of the hole will still fall short of the crust-mantle boundary by almost 4 kilometers.

And yet, reaching even 2 kilometers into the crust holds great promise of scientific discovery. Samples from these depths will yield a wealth of new scientific information that will expand our understanding of the formation of the oceanic plates that cover more than 60% of the surface of our planet.

Illustration by Sarah McNaboe (Integrated Ocean Drilling Program-U.S. Implementing Organization)

Comments

Have you actually gone all

Have you actually gone all the way to the core with a drill? If not, how do you know how far away it is from the crust? If so, what did it look like? Was there a camera on the drill?
-ELLEBOB

Temperature

How hot is it under the earth? in the mantle? Is the temperature the reason why you aren't going further? good luck with your mission!- HOTDOG

Questions

I admire that this group of people take their time and go out to the middle of the ocean to get samples to help us figure out more about the world we live on. I have a few questions to clarify my understanding... what type of tools do you use to get from 3,600 meters of water to drilling into the lower oceanic crust? Can the tools that you have reach the mantle or core? What would happen if you did reach the mantle and/or the core? What types of samples would you find? Would molten material come out and if it did, would anything happen to the ocean? I hope all of your goals are reached! :)

How we drill; how deep we can drill

To answer your question about the kind of tools we use to drill below the seafloor, take a look at the blog post from 4/29/11, "Inquiring Minds Want to Know: A Student Asks How We Drill." And no, we won't be able to reach Earth's mantle or core -- they're just too far beneath us. Remember that the ocean crust where we're drilling is 6 kilometers thick (take a look again at the diagram above, "Basic Layers of the Earth.") You also asked if we might drill down into molten material, or magma, on this expedition. No, there's no risk of that.

Plate Tectonics & Hi from Phoenix AZ!

Dear JOIDES Resolution,
We are a science class from Phoenix Country Day School in Paradise Valley, Arizona. We are studying plate tectonics and were extremely excited to come across your interesting blog. We all learned more about this fascinating topic and admire your extreme effort to expand our understanding of the earth by drilling farther into the oceanic crust than anyone has before. However, we have some questions for you about your blog and illustration. In the illustration, you did not include a lithosphere or an asthenosphere. In class, we learned that convection currents occur in the asthenosphere. On your illustration, the mantle was called solid, however, in order for convection to occur, the upper part of the mantle must be liquid. Also, what will happen when your drill hits the liquid portion of the mantle? Thank you for your time, and we wish you the best in your quest to discover more about the earth! We hope you have a great day and we <3 your face!!!!!!!!