Geology Midterm

Question 1

What 2 factors influence an object’s gravitational attraction?

Answer 1

Greater mass, greater attraction. Distance also affects attraction.

Question 2

What is responsible for igniting a star?

Answer 2

Nuclear fusion involving hydrogen and helium occurring in protostar.

Question 3

When was the first star born?

Answer 3

800 million years after big bang

Question 4

What is unique about first generation stars?

Answer 4

Larger, burn hotter, and run out of fuel faster.

Question 5

Systems Stellar nucleosynthesis

Answer 5

Heavier elements will form as a byproduct of fusion reactions.

Question 6

How do galaxies form?

Answer 6

Nebula material coming together in a disc.

Question 7

If the primary elements of the universe are hydrogen and helium (occurring in a 3:1 ratio), how do heavier elements (Ca, Fe, Si, O, etc.) occur in any type of concentration?

Answer 7

Stars go supernova and heavier elements spewed into galaxy when they were created when stars were born

Question 8

What does the Solar Nebula Theory (The Nebular Theory) specifically explain?

Answer 8

How solar systems are created.

Question 9

Ridge-Push

Answer 9

Lithosphere at mid ocean ridges lies at a higher elevation, gravity causes elevated lithosphere at the ridge axis to push lithosphere away from ridge

Question 10

Mineral

Answer 10

a naturally occurring solid, with a definite chemical composition and crystalline structure

Question 10

Slab-Pull

Answer 10

Downgoing plates are more dense than asthenosphere, therefore it willingly sinks, pulling the rest of the plate into the mantle with it

Question 11

Euhedral

Answer 11

perfectly shaped

Question 12

Subhedral:

Answer 12

imperfectly shaped

Question 13

Anhedral

Answer 13

lost its shape altogether

Question 14

Non-Silicate Mineral Groups

Answer 14

Native elements, Carbonates (CO-2), Oxides have O2, halides have halogens, sulfides have S, sulfates and phosphates

Question 15

Silicate Mineral Group

Answer 15

Most are silicates. Silicon tetrahedron. SiO4. Isolated tetrahedra do not bond with other silica tetrahedra: olivine and garnet, fracture as well. Single chain silicates are bonded. Pyroxenes are single chain silicates. Double chains are amphiboles. Mica group have a sheet structure, basil cleavage and peel into sheets

Question 16

regolith

Answer 16

loose debris (can be sediment, but mostly soils)

Question 17

Jointing

Answer 17

Natural crack or plane of weakness in a rock.

Question 18

Wedging

Answer 18

Joints are open further by freezing/thawing of water, salt precipitation, and plant roots.

Question 19

Sedimentary Rockbeds

Answer 19

layers on top of underlying basement rock

Question 20

basement

Answer 20

igneous or metamorphic or much older sedimentary rock. Platform for sediment to accumulate on where beds are created.

Question 21

What are the 4 processes that can form a sedimentary rock?

Answer 21

1) Cementing together loose clasts produced by weathering of pre-existing rock. Clastic rocks.
2) Growth of shell mounds/cementation of shell mounds
3) Accumulation/alteration of organic matter
4) Precipitation of minerals from surface water solutions

Question 22

Sedimentary Classification

Answer 22

o Clastic (detrital): cemented together clasts
o Biochemical: composed of shells
o Organic: C-rich relicts of plants/organism (coal)
o Chemical: Precipitates out of solution

Question 23

Turbidity Currents

Answer 23

Occur offshore, when shelf covered, sediments are deposited, water carves out canyons , water travels through and carries sediment. WHen reaches the end the sediment is dumped on the seafloor. An underwater avalanche.

Question 23

Graded Beds

Answer 23

Distinctively large grains on the bottom and fine grains on top

Question 24

o Bed-Surface Markings

Answer 24

Mud cracks
Raindrop impressions
Fossils

Question 25

o Imbrication

Answer 25

Large clasts are positioned in stacked arrangements in flow direction. Happens in conglomerates.