Geology 1001 Midterm: Ch. 5

Sedimentary environments are based on what 4 things?

1. Location & plate tectonic setting 2. Transport agent 3. Organic process modify sediments 4. Climate

Bioturbation is the reworking of soils and sediments by ____ and ____.

Animals, plants

How are clastic sedimentary rocks classified?

Based on their size of clast (rock fragments) that comprise them, grain size, chemical composition

Cross-bedding are sets of ____ ____ within rock layers that are ____ at angles as large as 35 degrees from the horizontal bed.

Bedded material, inclined

Clastic rocks are composed of predominantly ____ ____ or older weathered and eroded rocks.

Broken pieces

Diagenesis is the ____ of sediment's texture during and after formation.

Change

What are the 3 types of sedimentary rocks?

Clastic, biochemical, chemical

Diagenesis has what 3 steps?

Compaction, dewatering cementation & mineral changes

What are some effects of bioturbation?

Diagenesis, displacement of microorganisms and non-living particles

What are evaporite rock environments due to?

Evaporation of sea/lake water

In a current of water or air, the larger and denser grains fall ____ than the smaller grains.

Faster

What is a sedimentary environment?

Geographic location that has a peculiar combination of geological process

Sorting is a measure of what?

How similar grain sizes are within a sediment or rock

Sedimentary rocks cover most of what?

Land surface and seafloor

What is angularity the measure of?

Measure of the distance of transportation

Sedimentary structures are structures formed during what?

Sediment deposition

Size determines what?

Settling velocity

What are several examples of carbonate rock environments? What are they due to?

Shelled organisms, precipitation from seawater

What's the different between symmetrical ripples and asymmetrical?

Symmetrical -currents flowing opposite ways -equal slopes Asymmetrical -currents flowing same way -gentler & steeper slopes

Diagenesis occurs at ____ and ____ less than that required for metamorphic rocks.

Temperatures, pressures

Sorting tells us about the relative strength of what?

The current before it dropped its cargo

Your physical geography determines the what in the sedimentary rock cycle?

The dominant process at work in the sedimentary rock cycle

What does it mean when more of the corners of an individual grain in a clastic rock are rounded rather than angular?

The rock has been transported a longer distance

The physical features of sedimentary environments include was 2 things?

Water depth, persistence of currents

What 2 things does erosion include?

Weathering and transportation

What does cross-bedding indicate about the rock's climate?

Wind-blown conditions in either a desert or a beach

Bedding sequences are successions of rock that help geologists do what?

Work out the past environment

What does clast size indicate?

ancient relative current velocity

What sediments are formed in carbonate environments? Evaporite?

1. Carbonate sand/mud, reefs 2. Gypsum, borates, halite, other salts

Weathering is the ____ of rocks and is caused by what environmental features?

-Dissolving -Water, ice, acid, plants, animals, changes in temperature

What are the properties of poorly-sorted rocks vs. well-sorted?

-Poorly= large and small grains jumbled together -Well= All grains same size

Sediment deposition is caused by what and results in what?

-Wind, ice, water, gravity -Builds of layers of sediment