One Hundred One Thousand Meters
Iris van Zelst
At the surface
of the Earth,
rocks are
strong
A little
lower,
a little
less
Then strong again
and then
they
get
w
e
a
k
The Science
The lithosphere is the Earth’s rigid outer shell, which consists of the Earth’s crust and the upper part of the Earth’s mantle. Although commonly known as being the ‘rigid outer shell’, there are different types of deformation dominant at different depths in the lithosphere. The upper part of the crust and mantle are characterised by brittle deformation (the rocks break; they are called ‘strong’), whereas the lower part of the crust and the lower part of the lithosphere are characterised by ductile deformation (the rocks flow on very long time scales; the rocks are called ‘weak’). So, the shape of the poem emulates the strength profile of the lithosphere as it varies with depth in its characteristic ‘Christmas tree’ shape. Simultaneously, the text explains what is happening to the strength of the rocks when you descend deeper into the Earth. Hence, this poem explains the structure of Earth’s continental lithosphere, i.e., the shallowest 100 km of the Earth or indeed: the first one hundred one thousand meters.
The Poet
Iris van Zelst is an interdisciplinary geophysicist, focusing on the geodynamics and seismology of Venus and Earth. She currently works as a postdoctoral researcher at the German Aerospace Center (DLR) in Berlin, Germany. Besides research, Iris is an avid science communicator. She founded the EGU Geodynamics blog and was its editor-in-chief from 2017 to 2023. She also created 'Science Sisters' on YouTube: an interview series to explore career paths and issues in academia. She is currently developing QUARTETnary: the card game about the geological time scale to encourage learning about Earth’s history. For more information, check out her website: https://irisvanzelst.github.io.
Next poem: Surface (ab)normal by Megan Brown