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to melt, those minerals with the lowest melting temperatures are the first to melt. Should
melting continue, minerals with higher melting points begin to melt and the composition
of the magma steadily approaches the overall composition of the rock from which it was
derived. Most often, however, melting is not complete. The incomplete melting of rocks
is known as partial melting, a process that produces most magma.
According to Bowen’s reaction series, rocks with a granitic composition are
composed of minerals with the lowest melting (crystallization) temperatures—namely,
quartz and potassium feldspar. Also note that as we move up Bowen’s reaction series,
the minerals have progressively higher melting temperatures and that olivine, which is
found at the top, has the highest melting point. When a rock undergoes partial melting it
will form a melt that is enriched in ions from minerals with the lowest melting
temperatures. The unmelted crystals are those of minerals with higher melting
temperatures. Separation of these two fractions would yield a melt with a chemical
composition that is richer in silica and nearer to the granitic (felsic) end of the spectrum
than the rock from which it was derived.
In summary, Bowen’s reaction series is a simplified guide to understanding how
partial melting produces rocks of various compositions. As rock begins to melt, those
minerals with the lowest melting temperatures are the first to melt. As a result, partial
melting produces magmas enriched in low-melting temperature components and richer
in silica than the parent rock.

Task 2. Answer the following questions, using the vocabulary from Task 1.
1. What may happen if magma migrates through the crust?
2. What process is called assimilation?
3. Is the force of the injected magma often sufficient to dislodge blocks of “foreign”
rock?
4. When does the process of magma mixing occur?
5. What did Bowen successfully demonstrate?
6. What process is called partial melting?
7. What happens to the minerals as we move up Bowen’s reaction series?
8. What does Bowen’s reaction series help to understand?

Task 3. Using the information from the texts above complete the following
sentences:
1. A process when magma migrates through the crust and incorporates some of the
surrounding host rock, is called … .
2. The incomplete melting of rocks is called … .
3. A process when one magma body intrudes another that has a different composition
is called … .

Task 4. Choose the best answer:
1. As rock begins to melt, those minerals with the highest/the lowest melting
temperatures are the first to melt.
2. When a rock undergoes partial melting it will form a melt that is enriched in ions
from minerals with the highest/ lowest melting temperatures.
3. The unmelted crystals are those of minerals with higher/lower melting
temperatures.
4. Partial melting produces magmas enriched in low-melting/high-melting
temperature components.
5. Magma mixing may occur during the ascent of two/three chemically distinct
magma bodies as the more buoyant mass overtakes the more slowly moving mass.

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