geology lab practical

what is the relief of a topographic map?

maximum elevation minus minimum elevation

what direction do contour lines face on a river / stream?

the v faces upstream

what is the principle of relative time that states that the oldest rock layers are on the bottom and the youngest at the top?

superposition

which period of time is older, devonian or the cambrian?

cambrian

what is original horizontality?

sediments are originally deposited in horizontal layers

what are cross-cutting relationships?

rocks of features are younger than rocks or features they cut

what is lateral continuity?

sedimentary units extend laterally until they thin out to zero

what are inclusions?

rocks found within other rocks are older than their host rocks

what would a nonconformity look like in a cross section?

an igneous intrusion

which mineral group is the hydrochloric acid test particularly useful?

calcite

what would an angular unconformity look like in a cross section?

different in angles between some rock layers

which mineral property describes the color of a mineral’s powder?

streak

which mineral property describes breaking along flat planes that reflect light across them?

cleavage

moh’s scale of hardness (rock type for each hardness level)

1. talc

2. gypsum

3. calcite

4. fluorite

5. apatite

6. feldspar

7. quartz

8. topaz

9. corundum

10. diamond

what color is Na-plagioclase

white to light gray

what color is Ca-plagioclase

dark gray

what color is k-spar

light pink, peach, orange, brownish

what color is garnet?

red / honey brown

what color is magnetite

black

what color is olivine

green

what color is pyroxene

greenish black

quartz

serpentine

what color is hornblende

black, dark gray

hornblende

muscovite

what are igneous rocks classified on?

texture and mineral / chemical composition

phaneritic

igneous rock texture

crystals are greater than 1 mm in diameter

common phaneritic rocks

granite, diorite, gabbro, and peridotite

pegmatitic

igneous rock texture

crystals are larger than 25 mm in diameter

aphinitic

texture of igneous rocks

rocks form at surface or just below

crystals are too small to be distinguished by the unaided eye

pink or light gray color of igneous rock indicates

felsic (rhyolite)

gray color of igneous rock indicates

intermediate (andesite)

black or dark gray color of igneous rock indicates

mafic (basalt)

porphyritic

igneous rock texture

mix of large and small crystals

glassy

texture of igneous rocks

igneous rock texture

lack of mineral crystals

pyroclastic

igneous rock texture

fragmental texture

vesicular

highly porous and spongy

speed of cooling of igneous rock textures

pegmatitic —> rocks cooled VERY slowly

phaneritic —> rocks cooled slowly

aphanitic —> rocks cooled quickly (at or near the surface)

porphyritic —> rocks cooled at different rates

glassy —> form above ground, so cool very very quickly

pyroclastic—> super fast, volcanic breccias

vesicular —> quick cooling

what kind of texture does obsidian have?

glassy

what texture does pumice have?

glassy / vesicular

what are rocks that have crystallized from magma on the surface called?

extrusive or volcanic

what are the rocks formed beneath the surface called?

intrusive or plutonic

what rock textures correspond with intrusive conditions?

phaneritic and pegmatitic

what rock textures imply extrusive formation?

aphanitic, glassy, pyroclastic

two critical groups of mafic minerals that occur in igneous rocks

amphiboles and pyroxenes

how to tell the difference between amphiboles and pyroxenes

amphiboles cleave in two directions at 56 and 124 degrees

amphiboles are more black, pyroxenes are more green

common igneous amphibole

hornblende

way to distinguish between muscovite and biotite

muscovite is colorless to tan

biotite is black

diabase

what minerals does diabase contain? also what texture is diabase

primarily Ca-plagioclase and pyroxene

mafic

what minerals do granites usually contain?

Na-feldspar, K-spar, quartz, mica

texture and minerals of peridotite

pyroxene and olivine

phaneritic

classifications of igneous rocks

felsic, intermediate, mafic, ultramafic

what minerals does gabbro contain?

pyroxene, Ca-rich plagioclase, olivine

ultramafic rocks

peridotite

mafic rcks

diabase, basalt, gabbro

intermediate rocks contain what minerals?

biotite, Na-plagioclase, some K-spar

intermediate rocks

andesite

diorite

diorite

felsic rocks

rhyolite

granite

what class of sedimentary rocks are made up of broken rock fragments?

clastic

what is the mineralogy of limestones?

calcite and dolomite

what are two of the organic / biogenic sedimentary rocks?

limestone and coal

breccia and conglomerate environment

high energy such as vigorous river, mass movement landslide, glacial outwash

breccia fragment shape

angled fragments

conglomerate fragment shape

rounded fragments

sandstone environment

moderate energy environment — beach, medium to small river, dune, desert

quartz sandstone environment

beaches, continental shelves, dnes

arkosic sandstone environment

arid to semi arid

graywacke sandstone environment

tectonically active environment, shallow marine or river

arkose sandstone

siltstone environment

moderate to low energy environment

flood plain, river delta, shallow lake

shale environment

low energy like deep lake or deep marine

examples of inorganic sedimentary rocks

halite, calcite (limestone), dolomite, silica (chert)

chert

how to tell difference between gypsum and calcite

calcite reacts more vigorously with HCl

quartz arenite sandstone

what minerals are in graywacke sandstone?

quartz, plagioclase

graywacke sandstone

what two things are needed to make metamorphic rocks?

pressure and temperature / heat change

what are two main textures of metamorphic rocks

foliate and non foliate

name two metamorphic rocks

serpentinite and slate

slate

difference between slate and phyllite

phyllite has a little bit of sheen to it

what is strike slip fault?

right lateral and left lateral?

ground moves parallel to earth’s surface

right lateral right side moves down

left lateral right side moves up

where does hanging wall move in normal fault? reverse?

down

up in reverse / thrust fault

synclines plunge in the direction they ______

open