ESS 101 LAB EXAM SCRIPT WITH
CORRECT ANSWERS
◍ What could explain the asymmetry of magnetic stripes on the
ocean floor? Answer: The magnetic stripes represent fluctuating
polarity changes of the Earth's magnetic field preserved in the basaltic
ocean crust. The reversals have been dated using K-Ar dating
producing a paleomagnetic time scale
◍ What is the difference between fracture and cleavage for a mineral?
How can you distinguish between them when looking at a sample?
Answer: Fracture is the characteristic way a mineral breaks. The
difference between cleavage and fracture is that cleavage is the break
of a crystal face where a new crystal face is formed where the mineral
broke, whereas fracture is the "chipping" of a mineral.
◍ What does mafic mean? What are two mafic minerals? Answer:
Mafic is an adjective describing a silicate mineral or igneous rock that
is rich in magnesium and iron, and is thus a portmanteau of
magnesium and ferric. Most mafic minerals are dark in color, and
common rock-forming mafic minerals include olivine, pyroxene,
amphibole, and biotite.
◍ What does felsic mean? What are two felsic minerals? Answer: In
geology, felsic refers to igneous rocks that are relatively rich in
elements that form feldspar and quartz. ... Felsic refers to silicate
, minerals, magma, and rocks which are enriched in the lighter
elements such as silicon, oxygen, aluminium, sodium, and potassium.
◍ What does the Bowen's reaction series represent? Answer: Bowen
determined that specific minerals form at specific temperatures as a
magma cools. At the higher temperatures associated with mafic and
intermediate magmas, the general progression can be separated into
two branches.
◍ How do porphyritic-textured igneous rocks form? Answer:
Porphyritic rocks are formed when a column of rising magma is
cooled in two stages. In the first stage, the magma is cooled slowly
deep in the crust, creating the large crystal grains, with a diameter of
2mm or more.
◍ How does lava viscosity affect the slope of a volcano? Answer: the
more viscous the magmas a volcano erupts, the steeper the volcano.
Thus, shield volcanoes like we have in Hawai'i have gentle slopes
(less than 10 degrees), while stratovolcanoes like the Cascades in the
northwestern mainland are much steeper (roughly 25 degrees).
◍ What is a clastic sedimentary rock? Answer: Clastic rocks are
composed of fragments, or clasts, of pre-existing minerals and rock. A
clast is a fragment of geological detritus, chunks and smaller grains of
rock broken off other rocks by physical weathering. Geologists use
the term clastic with reference to sedimentary rocks as well as to
particles in sediment transport whether in suspension or as bed load,
and in sediment deposits.
CORRECT ANSWERS
◍ What could explain the asymmetry of magnetic stripes on the
ocean floor? Answer: The magnetic stripes represent fluctuating
polarity changes of the Earth's magnetic field preserved in the basaltic
ocean crust. The reversals have been dated using K-Ar dating
producing a paleomagnetic time scale
◍ What is the difference between fracture and cleavage for a mineral?
How can you distinguish between them when looking at a sample?
Answer: Fracture is the characteristic way a mineral breaks. The
difference between cleavage and fracture is that cleavage is the break
of a crystal face where a new crystal face is formed where the mineral
broke, whereas fracture is the "chipping" of a mineral.
◍ What does mafic mean? What are two mafic minerals? Answer:
Mafic is an adjective describing a silicate mineral or igneous rock that
is rich in magnesium and iron, and is thus a portmanteau of
magnesium and ferric. Most mafic minerals are dark in color, and
common rock-forming mafic minerals include olivine, pyroxene,
amphibole, and biotite.
◍ What does felsic mean? What are two felsic minerals? Answer: In
geology, felsic refers to igneous rocks that are relatively rich in
elements that form feldspar and quartz. ... Felsic refers to silicate
, minerals, magma, and rocks which are enriched in the lighter
elements such as silicon, oxygen, aluminium, sodium, and potassium.
◍ What does the Bowen's reaction series represent? Answer: Bowen
determined that specific minerals form at specific temperatures as a
magma cools. At the higher temperatures associated with mafic and
intermediate magmas, the general progression can be separated into
two branches.
◍ How do porphyritic-textured igneous rocks form? Answer:
Porphyritic rocks are formed when a column of rising magma is
cooled in two stages. In the first stage, the magma is cooled slowly
deep in the crust, creating the large crystal grains, with a diameter of
2mm or more.
◍ How does lava viscosity affect the slope of a volcano? Answer: the
more viscous the magmas a volcano erupts, the steeper the volcano.
Thus, shield volcanoes like we have in Hawai'i have gentle slopes
(less than 10 degrees), while stratovolcanoes like the Cascades in the
northwestern mainland are much steeper (roughly 25 degrees).
◍ What is a clastic sedimentary rock? Answer: Clastic rocks are
composed of fragments, or clasts, of pre-existing minerals and rock. A
clast is a fragment of geological detritus, chunks and smaller grains of
rock broken off other rocks by physical weathering. Geologists use
the term clastic with reference to sedimentary rocks as well as to
particles in sediment transport whether in suspension or as bed load,
and in sediment deposits.
