geo midterm

Volcanoes - Objective 8a What are the two types of lava flows?

Pahoehoe and Aa.

Volcanoes - Objective 8b Describe the physical characteristics of a pahoehoe lava flow.

Smooth, ropy, wrinkled surface.

Volcanoes - Objective 8c Describe the physical characteristics of an Aa lava flow.

Rough, sharp, jagged, blocky surface.

Volcanoes - Objective 8d Identify the lava flow type from its description: smooth, ropy, and wrinkled.

Pahoehoe.

Volcanoes - Objective 8e Identify the lava flow type from its description: rough, jagged, sharp, and blocky.

Aa.

Volcanoes - Objective 9a What are the main forms of pyroclasts?

Ash, lapilli, cinders, and bombs.

Volcanoes - Objective 9b List the main forms of pyroclasts from smallest to largest.

Ash → lapilli/cinders → bombs.

Volcanoes - Objective 10 What is the most deadly manifestation of a volcanic eruption?

Pyroclastic flows (nuée ardente): extremely hot, fast-moving mixtures of volcanic gas, ash, and rock fragments.

Volcanoes - Objective 11 Besides common eruptive characteristics, what physical surface features can indicate magma near Earth's surface?

Geysers, hot springs, travertine terraces, and fumaroles (steam/gas vents).

Volcanoes - Objective 12 What are the five warning signs used to predict volcanic eruptions?

Increased seismic activity, increased gas output, ground swelling, increased temperature, and strange animal behavior (less reliable).

Igneous Rocks - Objective 1a What is molten rock underground called?

Magma

Igneous Rocks - Objective 1b What is molten rock on Earth's surface called?

Lava

Igneous Rocks - Objective 2a What are the two categories of igneous rocks based on where they form?

Intrusive (plutonic) and extrusive (volcanic)

Igneous Rocks - Objective 2b Define intrusive (plutonic) igneous rocks, including their crystal size.

Form underground, cool slowly, and produce large crystals

Igneous Rocks - Objective 2c Define extrusive (volcanic) igneous rocks, including their crystal size.

Form on Earth's surface, cool quickly, and produce small crystals

Igneous Rocks - Objective 3a What are the seven principal igneous rock textures?

Glassy, aphanitic, phaneritic, pegmatitic, porphyritic, vesicular, pyroclastic

Igneous Rocks - Objective 3b Define glassy texture.

No crystals

Igneous Rocks - Objective 3c Define aphanitic texture.

Crystals smaller than 1 mm

Igneous Rocks - Objective 3d Define phaneritic texture.

Visible crystals larger than 1 mm

Igneous Rocks - Objective 3e Define pegmatitic texture.

Very large crystals greater than 2.5 cm

Igneous Rocks - Objective 3f Define porphyritic texture.

Large crystals surrounded by smaller crystals

Igneous Rocks - Objective 3g Define vesicular texture.

Contains gas bubbles or holes

Igneous Rocks - Objective 3h Define pyroclastic texture.

Composed of rock fragments from explosive eruptions

Igneous Rocks - Objective 4a What is the most common molecule in magma and lava?

Silica (SiO₂)

Igneous Rocks - Objective 4b What are the two most common gases dissolved in magma?

Water vapor (H₂O) and carbon dioxide (CO₂)

Igneous Rocks - Objective 5a What are the three main magma types based on composition?

Mafic (basaltic), intermediate (andesitic), felsic (rhyolitic)

Igneous Rocks - Objective 5b What are the phaneritic, aphanitic, and glassy rocks formed from mafic magma?

Phaneritic: Gabbro; Aphanitic: Basalt; Glassy: Obsidian

Igneous Rocks - Objective 5c What are the phaneritic, aphanitic, and glassy rocks formed from intermediate magma?

Phaneritic: Diorite; Aphanitic: Andesite; Glassy: Obsidian

Igneous Rocks - Objective 5d What are the phaneritic, aphanitic, and glassy rocks formed from felsic magma?

Phaneritic: Granite; Aphanitic: Rhyolite; Glassy: Obsidian

Igneous Rocks - Objective 6a Which minerals crystallize first in Bowen's reaction series?

Olivine and calcium-rich plagioclase

Igneous Rocks - Objective 6b Which mineral crystallizes last in Bowen's reaction series?

Quartz

Igneous Rocks - Objective 7 Besides crystallization order, what two things does Bowen's reaction series tell us?

The order minerals melt when heated and which minerals are most stable at Earth's surface

Igneous Rocks - Objective 8a What are the six igneous structures or features you must identify?

Country rock, plug (volcanic neck), sill, dike, baked zone, xenolith

Igneous Rocks - Objective 8b Define country rock.

Preexisting rock surrounding an igneous intrusion

Igneous Rocks - Objective 8c Define plug (volcanic neck).

Solidified magma inside a volcano's conduit, often exposed by erosion

Igneous Rocks - Objective 8d Define sill.

Sheet of intrusive igneous rock parallel to existing rock layers (concordant)

Igneous Rocks - Objective 8e Define dike.

Sheet of intrusive igneous rock cutting across existing rock layers (discordant)

Igneous Rocks - Objective 8f Define baked zone.

Surrounding rock altered by heat from an igneous intrusion

Igneous Rocks - Objective 8g Define xenolith.

Fragment of foreign rock enclosed within igneous rock; older than the surrounding rock

Igneous Rocks - Objective 9 How can you distinguish an igneous sill from a buried lava flow?

Sill: baked zones above and below; Lava flow: baked zone primarily below and vesicles near the top

Sedimentary Rocks - Objective 1a What are the four processes involved in forming sedimentary rocks?

Weathering, erosion, deposition, and lithification.

Sedimentary Rocks - Objective 1b Define weathering.

Breaking rocks into smaller pieces (sediment).

Sedimentary Rocks - Objective 1c Define erosion.

Movement of sediment from one location to another.

Sedimentary Rocks - Objective 1d Define deposition.

Placement of sediment at a new location.

Sedimentary Rocks - Objective 1e Define lithification.

Turning loose sediment into sedimentary rock.

Sedimentary Rocks - Objective 2a What are the two types of weathering?

Mechanical and chemical.

Sedimentary Rocks - Objective 2b Define mechanical weathering, including its causes and products.

Physically breaks rock into smaller solid fragments through impact, thermal expansion, or frost wedging. Produces clastic sediment.

Sedimentary Rocks - Objective 2c Define chemical weathering, including its causes and products.

Dissolves rock into individual molecules, especially in hot or acidic water. Produces dissolved material.

Sedimentary Rocks - Objective 3a What are the four agents of erosion?

Water, wind, gravity, and ice.

Sedimentary Rocks - Objective 3b Which agent of erosion is most important on Earth?

Water.

Sedimentary Rocks - Objective 3c Which agent of erosion is generally the only one able to move sediment uphill?

import manually

Sedimentary Rocks - Objective 4a What are the three ways sediment is transported in water?

Bed load, suspended load, and dissolved load.

Sedimentary Rocks - Objective 4b Define bed load.

Sediment rolls or bounces along the bottom of a waterway.

Sedimentary Rocks - Objective 4c Define suspended load.

Small particles remain suspended in water due to turbulence.

Sedimentary Rocks - Objective 4d Define dissolved load.

Dissolved rock material is transported in solution.

Sedimentary Rocks - Objective 5a What are the two types of deposition?

Chemical and clastic (detrital).

Sedimentary Rocks - Objective 5b Define chemical deposition and identify the type of rock it produces.

Dissolved minerals precipitate when water becomes saturated, producing chemical sedimentary rocks.

Sedimentary Rocks - Objective 5c Define clastic deposition and identify the type of rock it produces.

Solid rock fragments settle and accumulate, producing clastic sedimentary rocks.

Sedimentary Rocks - Objective 6a What happens to lakes created by dams?

Sediment accumulates behind the dam, gradually filling the reservoir through siltation.

Sedimentary Rocks - Objective 6b What happens directly downstream of dams?

Sediment-depleted water erodes the riverbed, causing degradation.

Sedimentary Rocks - Objective 7a What are the seven clastic sediment size classifications, from smallest to largest?

Clay, silt, sand, granule, pebble, cobble, boulder.

Sedimentary Rocks - Objective 7b What is the size range of clay, and what rock does it form?

Less than 1/256 mm; mudstone or shale.

Sedimentary Rocks - Objective 7c What is the size range of silt, and what rock does it form?

1/256–1/16 mm; siltstone.

Sedimentary Rocks - Objective 7d What is the size range of sand, and what rock does it form?

1/16–2 mm; sandstone.

Sedimentary Rocks - Objective 7e What is the size range of granules, and what rocks can they form?

2–4 mm; conglomerate if rounded or breccia if angular.

Sedimentary Rocks - Objective 7f What is the size range of pebbles, and what rocks can they form?

4–64 mm; conglomerate if rounded or breccia if angular.

Sedimentary Rocks - Objective 7g What is the size range of cobbles, and what rocks can they form?

64–256 mm; conglomerate if rounded or breccia if angular.

Sedimentary Rocks - Objective 7h What is the size range of boulders, and what rocks can they form?

Greater than 256 mm; conglomerate if rounded or breccia if angular.

Sedimentary Rocks - Objective 7i Define conglomerate.

Clastic sedimentary rock containing rounded coarse fragments.

Sedimentary Rocks - Objective 7j Define breccia.

Clastic sedimentary rock containing angular coarse fragments.

Sedimentary Rocks - Objective 8a What are the six clastic sedimentary rock types covered in the lecture?

Conglomerate, breccia, sandstone, siltstone, shale, and mudstone.

Sedimentary Rocks - Objective 8b Describe the depositional environment of conglomerate.

High-energy environments such as floods, debris flows, and mountain streams.

Sedimentary Rocks - Objective 8c Describe the depositional environment of breccia.

High-energy environments near the sediment source, where fragments remain angular.

Sedimentary Rocks - Objective 8d Describe the depositional environment of sandstone.

Mountain bases, fast-moving stream beds, and beaches.

Sedimentary Rocks - Objective 8e Describe the depositional environment of siltstone.

Slow-moving or still water, usually near shore.

Sedimentary Rocks - Objective 8f Describe the depositional environment of shale and mudstone.

Still, deep, calm water, usually far from shore.

Sedimentary Rocks - Objective 8g How does water energy affect the size of deposited clastic sediment?

High-energy water transports larger particles; smaller particles settle in lower-energy water.

Sedimentary Rocks - Objective 9 What is the most common characteristic of chemical sedimentary rocks?

They are generally composed predominantly of one mineral.

Sedimentary Rocks - Objective 10a What are the five major chemical sedimentary rocks?

Limestone, dolostone, chert, rock salt, and rock gypsum.

Sedimentary Rocks - Objective 10b What is the mineral composition of limestone?

Calcite (CaCO3).

Sedimentary Rocks - Objective 10c What is the mineral composition of dolostone?

Calcium-magnesium carbonate.

Sedimentary Rocks - Objective 10d What is the mineral composition of chert?

Silica (SiO2); varieties include flint, jasper, and agate.

Sedimentary Rocks - Objective 10e What is the mineral composition of rock salt?

Halite (NaCl).

Sedimentary Rocks - Objective 10f What is the mineral composition of rock gypsum?

Gypsum (CaSO4·2H2O).

Sedimentary Rocks - Objective 11a Describe the depositional environment of evaporites.

Bodies of water with high evaporation, usually closed basins where water enters but cannot flow out.

Sedimentary Rocks - Objective 11b Describe the depositional environment of carbonates.

Water with little or no clastic sediment, such as sheltered shallow bays or areas far from clastic input.

Sedimentary Rocks - Objective 11c Where is the Carbonate Compensation Depth (CCD)?

import manually

Sedimentary Rocks - Objective 11d How does the Carbonate Compensation Depth affect carbonate deposition?

import manually

Sedimentary Rocks - Objective 12a What was being mined at Lake Peigneur, Louisiana?

Salt from an underground salt mine within a salt dome.

Sedimentary Rocks - Objective 12b What happened to Lake Peigneur?

Drilling penetrated an underground salt mine, allowing lake water to rush in. The mine flooded, the ground collapsed, and the lake drained before refilling.

Sedimentary Rocks - Objective 12c Who was responsible for the Lake Peigneur disaster?

import manually

Sedimentary Rocks - Objective 13a What three characteristics of clastic sediment help determine depositional environment or transport distance?

Sorting, roundness, and particle size.

Sedimentary Rocks - Objective 13b What are the three main degrees of sediment sorting?

Well sorted, moderately sorted, and poorly sorted.

Sedimentary Rocks - Objective 13c Define well-sorted sediment and explain what it indicates.

Particles are nearly the same size, indicating relatively constant transport energy.

Sedimentary Rocks - Objective 13d Define moderately sorted sediment and explain what it indicates.

Particles have a relatively narrow size range, indicating moderate energy fluctuations.

Sedimentary Rocks - Objective 13e Define poorly sorted sediment and explain what it indicates.

Particles have widely different sizes, indicating drastic energy changes or rapid deposition.

Sedimentary Rocks - Objective 13f How does sediment sorting vary among depositional environments?

Mountains: poor; rivers: moderate to poor; lakes, beaches, nearshore: well; wind and offshore: very well sorted.

Sedimentary Rocks - Objective 13g How does particle roundness indicate transport distance?

Angular particles generally traveled shorter distances; rounded particles generally traveled farther.

Sedimentary Rocks - Objective 13h How does particle size indicate depositional energy and transport distance?

Large particles require high energy and tend to remain near their source; small particles settle in low-energy environments and often travel farther.

Sedimentary Rocks - Objective 14a What are the three processes of lithification?

Compaction, cementation, and recrystallization.