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Name:___________________
Date:_____________
Adapted from: http://www.cotf.edu/ete/modules/volcanoes/vinside.html
Looking Inside Earth DBQ
Although the interior of Earth is only a few tens of miles beneath our feet, it is more difficult to
reach than the surface of Pluto or even a nearby star! The deepest mines in the world are only
three to four kilometers deep. The deepest well ever drilled, located in Russia’s Kola Peninsula
only penetrates 12 kilometers into the interior at a cost of more than $100 million. The rocks at
the bottom are 2.7 billion years old with a temperature of 190 º degrees C, almost double the
boiling point of water. Since it is 6371 kilometers to the center of Earth, comparatively speaking,
we have not even been able to get through the skin of an apple. Why haven't we gone any
deeper? Even at a depth of 12 kilometers, the high pressures and temperatures of the surrounding
rock cause the metal of even the strongest drills to quickly weaken and deform. At depths of 100
kilometers, rock flows like butter, and any hole we could form would quickly close.
Yet we have learned a good deal about Earth's interior using indirect means. Earthquakes and
nuclear explosions generate sound (seismic) waves that travel through the entire volume of
Earth. By measuring the intensity and timing of seismic waves at many locations on the surface
of Earth, we are able to determine the density of materials at different levels in the interior. (The
technique is a very sophisticated version of tapping on a barrel or wall to see if there is
something inside.) By measuring the properties of different materials under high pressure in the
laboratory, we can make a good estimate of the composition of different parts of Earth's interior.
From all these measurements, we find Earth's interior is layered something like
the inside of an apple. The core of the apple is similar to the center of Earths
core. It is made mostly of iron, some nickel, and about 10 to 15% of a less dense
material, probably silicon, oxygen, or sulfur. The core itself is made of two
concentric pieces, a solid inner core and a liquid outer core.
The large zone corresponding to the flesh of the apple is called the "mantle". It is made mostly of
rocky minerals with names like olivine, pyroxene, quartz, and periclase. (Any good book on
geology or mineralogy will tell you everything you ever wanted to know about these minerals.)
Almost all rocks are made of silicon and oxygen mixed with other elements such as calcium,
aluminum, and iron. Mantle rock contains particularly large amounts of iron and magnesium.
The mantle is also divided into two solid parts, the lower mantle and the upper mantle. This
division in the mantle may be due to small differences in the amounts of iron and magnesium or
to differences in the nearness of atoms to each other. (As an analog, think of a piece of
Styrofoam. If you crush it, the particles inside move closer together because you have closed the
tiny open spaces inside, but it is still made of Styrofoam.)
Answers must be identified in the reading and all answers must be answered in complete
sentences!!!
1. How deep and where is the deepest well ever drilled?_________________________________
_____________________________________________________________________________.
2. What indirect means have scientist used to study the interiors of the earth? _______________
_____________________________________________________________________________.
3. What two elements are almost all rocks made up of? _________________________________
_____________________________________________________________________________.
4. What two elements make up the core of the Earth? ___________________________________
_____________________________________________________________________________.
5. What layer of the core is believed to be liquid? ______________________________________
_____________________________________________________________________________.
6. Why haven’t scientists explored the interiors of the Earth beyond 12 kilometers?
______________________________________________________________________________
_____________________________________________________________________________.
Using your Earth Science Reference Tables to answer the following questions:
1. What is the pressure (in millions of atmospheres at a depth of 1000 km ______________
2. What is the temperature in degrees Celsius of the Earths interior at the stiffer mantle,
outer core boundary? __________________________.
3. What two layers is the MOHO (Mohorovicic discontinuity) the boundary between?
_______________________________________________________________________.
4. What is the approximate density of the inner core? ______________________________.
5. At 4000 km below the Earths surface, what is the actual temperature of the earth? _____.
What is the melting point temperature of the Earths materials at 4000 km? ___________.
Does this make the Earths outer core a solid or a liquid? __________________________.