Five Things All College Students Should Know About the Earth

By Erik Klemetti | August 28, 2018 2:13 pm
The Horn of Africa seen from the International Space Station in January 2015, taken by ESA astronaut Samantha Cristoforetti. NASA.

The Horn of Africa seen from the International Space Station in January 2015, taken by ESA astronaut Samantha Cristoforetti. NASA.

So, another school year starts Thursday (for me) and I thought I’d offer a list of 5 things all college students should know about the Earth, whether they take a geology classes or not (but you really should take at least one).

#1 The Earth is 4.54 billion years old (give or take a few million years)

This is “long history”. About 4.54 billion years ago, the Earth was formed out of the pile of debris and gases that surrounded our just-born Sun. How do we know this? By determining the age of meteorites that match the composition of the early solar system using the isotopes produced by radioactive decay. We can find some evidence of the first minerals produced in the early Earth by dating zircon at the Jack Hills in Australia, and they reach back to about 4.4 billion years ago. Modern Homo sapiens have only been around for a whopping 0.004% of the history of our planet.

#2 Rocks record the evidence of evolution of life on Earth

Speaking of when Homo sapiens arrived on the scene, the rocks of Earth contain all the evidence for evolution as the driving mechanism for the diversity of life on Earth. Since life appeared ~3.8 billion years ago, rocks have been capturing a long (and somewhat incomplete) record of organisms that existed on land and in the seas. It is this “long history” that is needed to really appreciate how life has changed to meet the demands of a changing planet.

#3 Inside the Earth, rocks melts (but not for the reason you think)

Lava fountaining from fissure 8 on Kīlauea's lower East Rift Zone in June 2018. USGS/HVO.

Lava fountaining from fissure 8 on Kīlauea’s lower East Rift Zone in June 2018. USGS/HVO.

We know that rocks melt. The eruption in Hawaii this past summer is evidence enough that molten rocks reach the Earth’s surface. However, many people think that rocks melt inside the Earth because it is hot down there (and it is!) … but that’s not the case in most places. Instead, rocks are melting because they are great insulators, so they keep their heat from deep within the Earth as they rise. The trick is that the melting point of rock goes down as the pressure goes down, so hot rock will melt as they rise. Secondly, when water trapped in rocks is released as they heat up in the Earth, that water can lower the melting point of rock kind of like salt does for ice. This means rock that wouldn’t normally melt does. The former is the source of lava in places like Hawaii and Iceland while the latter drives volcanism in the Andes or Cascades.

#4 Speaking of which, the interior of the Earth is not molten (except for one layer)

All that being said about melting rocks, the inside of the Earth is not one big molten pool on which continents are floating. Instead, the mantle — the layer directly below the Earth’s crust — is a flowing solid that is hot and convecting. The outer core of the Earth is liquid, but instead of liquid rock (magma), it is liquid iron and nickel metal. This layer moves around, which forms the Earth’s magnetic field. However, if you go down even deeper, the Earth becomes solid again because the high pressure of the Earth’s core means that the iron and nickel exist as a solid again.

#5 The surface of the Earth is always changing

The Franklin Mountains in Texas. Wikimedia Commons.

The Franklin Mountains in Texas. Wikimedia Commons.

As James Burke of the famed series Connections would say, the only constant on Earth is change. The surface of the Earth is dynamic and over the planet’s long history, not only has the surface experienced weathering and erosion caused by the Earth’s water and atmosphere, but the whole surface has changed. This is thanks to plate tectonics, where the continents and oceanic plates move around over hundreds of millions of years, reshaping the look of the planet from one with one massive supercontinent to today’s more spread out version. Mountain ranges go up and come down, ocean basins open and close, glaciers rampage over the land and then retreat. Something new is always happening.

#6 (Yes, a bonus) The Earth’s climate changes, but this time it is our fault

Finally, the Earth’s climate — the long-term record of the planet’s surface conditions — is also changing, just like the surface of the Earth itself. These changes have been going on for billions of years due to influences like the orbit and tilt of the planet, impacts of comets or asteroids, massive volcanic eruptions, the evolution of life and a myriad of other factors. However, the rapid change we are experiencing today is due to the direct impact of humans releasing massive amounts of carbon dioxide into the atmosphere through the burning of fossil fuels. The planet has survived climate change before, but the life on Earth doesn’t always fare so well.

There you go, six things everyone should know about geology. There is much more you can discover, so do yourself a favor and take some geology, read some books and get to know the planet that we all live.

 

CATEGORIZED UNDER: Rocky Planet, Science, Science Blogs
ADVERTISEMENT
  • http://www.mazepath.com/uncleal/EquivPrinFail.pdf Uncle Al

    The Earth is flat, but rolled into a solid cylinder.

    direct impact of humans releasing massive amounts of carbon dioxide” Summed annual anthropogenic carbon dioxide emissions are negligible compared to summed annual planetary wildfire emissions,

    workingonfire(.)com(.)br/wp-content/uploads/2017/07/World-Fires-Wof-Int.jpg
    earthobservatory(.)nasa(.)gov/global-maps/MOD14A1_M_FIRE

    • Boofungus

      Oh yes, and a human body temperature of 103 is also a neglible rise above the norm, so don’t worry next time you run a high fever…

      • http://www.mazepath.com/uncleal/EquivPrinFail.pdf Uncle Al

        Dip your finger into molten iron.

  • Mike Richardson

    It’s a shame that most of these principles are controversial to some because of religious or political dogma. A person’s ideology should be based on reality, supported by objective facts, and not the other way around.

    • DodgeMiniVan

      I agree with you 100%; Our astronauts have also proven, The Earth IS Round.

  • jimgrot

    thinly veiled global warming alarmist, too bad, it was relatively good ’til the bonus propoganda

    • EquusMtn

      Science isn’t propaganda. Propaganda is what fossil fuel-based corporations, Fox News, and the Republican party want the masses to believe.

  • whheydt

    Nice to see the reference to James Burke and _Connections_.

  • Bill

    “Bonus fact: It’s round.”

    I’ll assume that was a headline teaser authored by a junior assistant editor 3rd class, since we all know the Earth is not round, or more accurately the Earth is not a sphere. The Earth is an oblate spheroid, its diameter being approximately 27 miles less through the poles than through the equator.

NEW ON DISCOVER
OPEN
CITIZEN SCIENCE
ADVERTISEMENT

Rocky Planet

Rocky Planet covers all the geologic events that made and will continue to shape our planet. From volcanoes to earthquakes to gold to oceans to other solar systems, I discuss what is intriguing and illuminating about the rocks beneath our feet and above our heads. Ever wonder what volcanoes are erupting? How tsunamis form and where? What rocks can tell us about ancient environments? How the Earth might change in the future? You'll find these answers and more on Rocky Planet.
ADVERTISEMENT

See More

ADVERTISEMENT

Discover's Newsletter

Sign up to get the latest science news delivered weekly right to your inbox!

Collapse bottom bar
+