Geophysicist Shares a Song of Earth's Polarity

The SoundClips series continues with a submission from listener Dave Engebretson. Engebretson has been legally blind all of his life, so he pays special attention to sound. He submits audio that is analogous to the history of Earth's magnetic field reversals.

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MELISSA BLOCK, host:

In addition to thermal energy, the Earth also generates the magnetic kind. A listener turned the reversals of Earth's polarity into a musical representation. And that's our SoundClip for today.

Dr. DAVE ENGEBRETSON (Geophysicist, Western Washington University): My name is Dave Engebretsen. I'm a geophysicist and teach geology at Western Washington University in Bellingham, Washington. I've been blind since birth so I've had a great opportunity to learn how vital and interesting sound is on our daily lives.

In the last few years, I've lost most of my remaining vision and have turned my attention to using sound in both research and teaching and as a hobby. I've come to realize that vision seems to be overrated just about as much as the use of hearing is overlooked. With this in mind, I want to share some science that has been rendered into the audio room.

One of the most incredible data sets available under science is the long history of reversals in Earth's magnetic field as recorded in the oceanic crust of the world. Earth's magnetic field is flipped about a hundred and eighty times in the last 85 million years and provided rich data set to study. This alternating magnetic field originates in the liquid outer core, deep in to about 2900 kilometers from the surface.

(Soundbite of recorded Earth's magnetic field)

Mr. ENGEBRETSON: We let the length of the polarity intervals control the frequency. Short time intervals are high frequency and vice versa. And they are registered to a two millimeter(ph) per second audio stream.

(Soundbite of recorded Earth's magnetic field)

Mr. ENGEBRETSON: My ears tell me there are some recognizable pattern such as a sort of point-counterpoint or question and answer that occurs during the song, maybe three different movements. And the noticeable increase in frequency of reversals as we approach today.

BLOCK: Listener Dave Engebretsen of Bellingham, Washington tracing patterns of polarity reversal of the planet Earth in music.

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