earth's materials: minerals & rocks (#2)

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1. naturally occurring

2. inorganic

3. homogeneous solid

4. has definite chemical composition

5. ordered crystalline structure

5 characteristics of minerals

color

PHYSICAL PROPERTIES OF MINERALS:

Wavelength of light reflected by the mineral;

Most noticeable physical property;

greatly affected by impurities

• can be idiochromatic, allochromatic, or pseudochromatic

streak

PHYSICAL PROPERTIES OF MINERALS:

color of a mineral in its powdered form;

more reliable in mineral identification than color

luster

PHYSICAL PROPERTIES OF MINERALS:

quality of reflected light of a mineral’s surface;

can be metallic or non-metallic

hardness

PHYSICAL PROPERTIES OF MINERALS:

measure of resistance of a mineral to abrasion;

measured by scratching mineral with another object of known hardness

• Mohs scale of hardness

Mohs scale

this is used to measure a mineral’s hardness;

this is composed of 10 minerals, numbered from 1 to 10 (1 as the softest and 10 as the hardest);

a relative and not qualitative measure of the mineral's hardness

True

TRUE OR FALSE:

The scale does not mean that calcite is not thrice as hard as talc. The Mohs scale just indicates that calcite is harder than talc.

cooling & crystallization

ROCK CYCLES:

rocks that are deep under the earth’s surface have a chance to melt into magma and cool (called ______), and when these crystals form from magma, this process happens;

forms igneous rocks

(should have 2 answers)

metamorphism

ROCK CYCLES:

What process happens when rocks that are exposed to high temperatures and pressures within the crust form a metamorphic rock?

• 4 types: contact, burial, regional, and dynamic

weathering

ROCK CYCLE:

this process is related to the breaking of rocks which depends on the parent material and the environmental conditions;

this can break down large rocks into smaller rocks called sediments

• mechanical, chemical, & biological

erosion

ROCK CYCLES:

this happens when moving water and wind carry these rocks to one place or another, basically the displacement of these rocks

lithification

ROCK CYCLES:

process where these sediments harden to become sedimentary rocks

igneous rocks

TYPES OF ROCKS:

these are deep under the earth’s surface and have a chance to melt into magma and cool;

formed by cooling & crystallization

• 2 class. based on location: intrusive/plutonic & extrusive/volcanic

intrusive/plutonic - granite, diorite

IGNEOUS ROCKS (LOCATION):

these are those that solidify below earth’s surface

(give examples)

extrusive/volcanic - basalt, andesite, obsidian

IGNEOUS ROCKS (LOCATION):

these are those that solidify above earth’s surface

(give examples)

sedimentary

TYPES OF ROCK:

these are rocks formed from lithification and where fossils are typically found;

• 2 ways to classify: clastic/detrital & chemical rocks

clastic rocks - sandstone, shale, mudstone

2 WAYS TO CLASSIFY SEDIMENTARY ROCKS:

this differentiates rocks in terms of size;

formed from fragments or "clasts" of pre-existing minerals and rocks, broken down by weathering and erosion, and then cemented together

(give example)

chemical rocks - dolomite, limestone

2 WAYS TO CLASSIFY SEDIMENTARY ROCKS:

these are formed from dissolved compounds and ions in solution which happen during chemical weathering

shale

this is the most abundant sedimentary rock on earth and formed from clay & silt

depositional environment

an accumulation of chemical, biological, and physical properties and processes associated with the deposition of sediments that lead to a distinctive suite of sedimentary rocks;

where sediments are deposited;

most commonly seen in areas with sources of water

metamorphic

TYPES OF ROCK:

these are rocks that have been altered, changed, or transformed in the solid-state due to changes in pressure, temperature conditions, and chemical actions of hot fluids;

• 2 types: foliated & nonfoliated

foliation

UNDER METAMORPHIC ROCKS:

this is caused by extreme forces of heat and pressure pressing parallel layers of minerals into denser, distinguishable layers;

pervasive layering caused by compositional layering or by the parallel orientation of platy (e.g, mica) or elongate (e.g., amphibole) mineral grains

foliated - slate, schist

2 TYPES OF METAMORPHIC ROCKS:
these rocks produce evident lines or bands at the surface

(give example)

non-foliated metamorphic rock - marble

2 TYPES OF METAMORPHIC ROCKS:
these rocks have no layers and lack a banded appearance

(give example)

igneous, sedimentary, & metamorphic rocks

3 rock types

burial

4 TYPES OF METAMORPHISM:

due to lithostatic pressure

contact

4 TYPES OF METAMORPHISM:

magmatic heat and fluids act to produce change

dynamic

4 TYPES OF METAMORPHISM:

result of high differential pressures associated with intense deformation along faults

regional

4 TYPES OF METAMORPHISM:

occurs within a large area and caused primarily by mountain-building forces

geological time scale

system of chronological dating that relates geological strata to time

Geologic time

UNDER GTS:

this is the period covering the physical formation and development of the Earth before any recorded human history

Relative Age

UNDER GTS:

determines which rock, fossil, or event happens first

Stratigraphy

UNDER GTS:

study of rock strata or layers; strata means layers of rock or sediment

Numerical age

UNDER GTS:

determines the actual age of a rock by radiometric dating

radiometric dating

UNDER GTS:

method used to date rocks and other objects based on the known decay rate of radioactive isotopes

radioactive decay

UNDER GTS:

process by which the nucleus of an unstable atom loses energy by emitting high-energy particles

precrambrian

TIME DIVISIONS:

covers around 88% of the GTS;

informal unit of time;

• 3 eons: Hadean, Archean, Proterozoic

Paleozoic, Mesozoic, Cenozoic

3 eras of the Phanerozoic eon wherein visible life has been observed

Paleozoic era

3 PHANEROZOIC ERAS:

life in the early period of this era was dominated by marine organisms but by the middle of the era plants and animals evolved to live and reproduce on land;

first air-breathing tetrapods & amphibians evolved reptiles with the amniotic egg;

includes Carboniferous period;

Pangaea began to form near the end of this

Mesozoic era

3 PHANEROZOIC ERAS:

best known as the age of reptiles, most notably, the dinosaurs;

follows the Permian Mass Extinction;

first appearance of frogs, turtles, icthyosaurs & pleiosaurs, birds;

angiosperms (flowering & seed-bearing) originated during the Cretaceous;

• ended with the K-PG Mass Extinction

Cenozoic era

3 PHANEROZOIC ERAS:

a.k.a. age of mammals because they came to be dominant and large after giant reptiles’ extinction & includes the rise of man;

began 66 million years ago;

subdivided into epochs;

North America's characteristic landscapes began to develop

dissolution

process by which soluble rocks such as limestone (predominantly calcium carbonate), chalk (also calcium carbonate), dolomite (magnesium calcium carbonate), gypsum (hydrated calcium sulfate), and halite/“rock-salt” (sodium chloride) are dissolved by the passage of water or weakly acidic water either over the rock surfaces or through fractures and pores in the rock