Module 7

Question 1

Position major Earth events in historical sequence (geological time):
[Precambrian, Paleozoic, Mesozoic, Cenozoic Eras]

Answer 1

Cenozoic (65 Million years ago to present)
Mesozoic (251-65 Million y/a)
Paleozoic (542-251 My/a)
Precambrian (>542 My/a)

Question 2

Describe the cycle of rock transformation

Answer 2

• magma cools and crystallizes to igneous rock
• igneous rock can be weathered or pressured into sedimentary rock or heated to metamorphic rock
• sedimentary rock under heat and pressure recrystallizes to metamorphic rock
• metamorphic rock is either weathered back to sedimentary or melted to magma

Question 3

Define the rock type intrusive igneous rock (granite, gabbro) and extrusive igneous rock (basalt, obsidian),

Answer 3

intrusive: magma intrudes and cools with crustal rocks
- slow cooling produces coarse grained rocks
extrusive: magma is erupted as lava and cools on Earth’s surface
- rapid cooling produces fine-grained or glassy rocks

Question 4

Define the rock type sedimentary rocks (clastic, chemical, organic)

Answer 4

Begins at the products of rock weathering (clastic sediments), accumulation of calcareous minerals ( chemical sediments), accumulation of organic matter ( organic sediments)
and is created through processes of erosion, transport and deposition sediments; then lithification– compaction, cementation

Question 5

Define the rock type metamorphic rocks (gneiss, marble)

Answer 5

Igneous and sedimentary rocks are transformed by Heating and great pressure to Form metamorphic rocks

• rocks become harder and more resistant to erosion
• metamorphism may involve creation of new minerals and/or changes to Mineral arrangement
• distinguish between foliated (gneiss) and non-foliated rocks (quartzite, marble)

Question 6

Describe the physical properties of the continental crust, and oceanic crust

Answer 6

Continental crust:

• 30 km thick beneath continents; 50 to 60 km thick beneath mountains
• average density is 2700 kg/m3
• rich in silica (SiO2), aluminum, potassium, sodium, calcium; sial
• composed mainly of granite ( an intrusive igneous rock) and gneiss ( a metamorphic rock)

Oceanic crust:

• 5 km thick beneath ocean basins
• average density is 3000 kg/m3
• rich in silica, magnesium, iron; sima
• composed mainly of basalt ( and extrusive igneous rock) and gabbro (an intrusive igneous rock)

Question 7

Explain how the lithosphere plates move

Answer 7

Tectonic plates float on the asthenosphere and are moved by convection Loops driven by geothermal activity; magma plumes rise to the crust, spread horizontally and cool, moving segments of crust

Question 8

Describe folding and faulting at convergent and divergent plate boundaries

Answer 8

Convergent boundaries occur in areas of Crustle collision and subduction, where areas of continental and oceanic lithosphere meet, crust is compressed and then lost in a distraction or process as it moves downward into the mantle

Question 9

What is orogenesis?

Answer 9

The collision of tectonic plates that produces mountains.

There are two types: oceanic plate and continental plate

Question 10

Describe faults at transform plate boundaries

Answer 10

Transform boundaries occur where plates slide past one another, usually at right angles, to a seafloor spreading center. these are the fractured stretching across the mid-ocean ridge system worldwide
as plates move past each other horizontally, they form a type of fault, or fracture, in Earth’s crust called a transform fault

Question 11

What is subduction?

Answer 11

the sideways and downward movement of the edge of a plate of the earth’s crust into the mantle beneath another plate.

Question 12

Explain how volcanoes are made and their two types.

Answer 12

A mountain or a large Hill containing a conduit that extends down into the upper mantle, through which magma and gases are periodically ejected onto Earth’s surface or into the atmosphere

Explosive Volcanoes or Composite Volcanoes: Build-up and grow over several eruptions; eruptions are violent; characterized by steep slopes and small surface area
Effusice Volcanoes or Shield Volcanoes: Volcanoes with a very fluid eruptions; have gently sloping sides

Question 13

Describe the processes that create mid-oceanic ridges and oceanic trenches.

Answer 13

Endogenic processes contribute to the creation of landscapes of high topographic relief
Ex) mountains, volcanoes, mid-oceanic ridges, oceanic trenches
oceanic ridges and trenches are essentially underwater mountains??