Lynn Carter

microwaves to radio waves so not the visible light that we're all familiar with and these long wavelengths the advantage of them is that they can penetrate pretty far into the surface and the depth of penetration depends on the wavelength and so generally you can penetrate maybe about 10 times the wavelength into the surface and so that gives you a rough idea so if you want to penetrate farther into the surface you want the longest wavelength radar possible

So this is sort of the realm that we're living in in the radar space.

And also, there are two types of radars, at least this is how I think about it.

So some of you may be familiar with the shuttle radar pictures or orbital radar pictures.

And this one right here is a space shuttle radar picture, which is, this is the Sahara Desert, and the radar strip is here.

And so it's an image.

And the image here has just been superposed on top of an optical image.

and the radar reveals all of this buried stuff that you can't see optically.

So you can see all these channels.

These are old fluvial channels in the Sahara Desert when the climate of the Sahara was very different, and you actually had flowing water on the surface that carved lots of channels.

These images are also really good for archaeology.

They've been used to find, like, tombs, for example.

Now, if you have very high resolution, like with an airplane.

So it's very useful for seeing under things that you would otherwise just never be able to tell anything about.

Another type of radar, there's a lot of similarities, but I kind of think of them as a bit different.

These tend to be longer wavelength and they're called ground penetrating radars or sounding radars.

And so for this type of radar, instead of getting a picture like this that you overlay on other pictures and seabury things, you actually have a profile where this is along a track.

Say if you pulled a radar across the surface or if you had an airplane that flew along here,

and this is the depth so you actually have a slice of the surface and so in this case you're also seeing channels but this is a different type of thing so this is actually from a beach area near Boston where you've had lots of migration of fluvial channels back and forth and then other sediments getting deposited on the top and so at this top you can see there's some sediments up here but then there's this buried channel that you're seeing which is where the water previously flowed in the beach environment

but now that channel has migrated someplace else and it's all filled in.