EES 220 Exam 1 Review

What are the processes by which minerals are formed in nature?

-crystallization from a cooling melt -precipitation from a solution(cooling of hot water solutions, evaporation) -solid-state diffusion

What are some components of and problems with the simplified "scientific method"?

1. observation 2. question 3. hypothesis 4. test 5. theory problems: human reasoning is not always inductive, humans have pre-existing bias, prejudices, misconceptions, limited rnges of experience, and a knack for making mistakes

Be able to define or discuss aspects of the 6 processes that form sedimentary rocks

1. weathering -physical or chemical 2. erosion -action of surface processes that remove earth materials from one location to another 3. transport -through water, wind, or ice -requires energy -reduces grain size -rounding and sorting -removal of unstable minerals 4. deposition -clastic or chemical sediments 5. burial -in sedimentary basins 6. diagenesis - physical and chemical changes leading to lithification

What is science? What isn't science?

A complex web of attitudes, speculations, methods, and undertakings about the nature of the objective universe, which in the final analysis must satisfy a community of people who want to see their underlying commitment to truth satisfied.

What is a mineral?

A substance which meets the following criteria: homogeneous, solid, naturally-occurring, not an organic compound, definable chemical composition, orderly internal arrangement of atoms, ions, or molecules (crystal structure)

What are the effects of silica and water content on the eruptive behavior of magmas?

As silica content goes up the viscosity goes down which causes different types of lava flows Dry magmas erupt fairly passively while wet magmas have the potential to erupt more explosively

Mineral compositions of common igneous rock types: here are some sample questions: "What is the name of a fine-grained rock dominated by olivine and pyroxene? or "Name two minerals that commonly crystallize from mafic magmas".

Basalt, andesite, rhyolite, peridotite, gabbro, diorite, granite

What are some characteristics of basaltic and rhyolitic lava flows?

Basaltic (low silica) -erupted at 1000-1200 degrees C -low viscosity -fairly dry -two types are pahoehoe and aa Rhyolitic (high silica) -erupted at 800-1000 degrees C -high viscosity -dry to wet

Be able to identify types of igneous intrusions from photos or diagrams (these photos may or may not be the ones I showed in class)

Dikes - tabular intrusions that cut across structures in adjacent rocks (shiprock, new mexico) sills- tabular intrusions that parallel structures (layering) in adjacent rocks (palisades sill) Laccoliths-shallow, blister-shaped intrusions that have domed up overlying rocks (bear butte) plutons- irregular or blob shaped intrusions ranging up to km's across (stone mountain) batholiths - vast areas intruded by numerous plutons (Sierra Nevada Batholith)

What is geology? Physical Geology?

Geology is the scientific study of the Earth Physical Geology is the division of geology concerned with earth materials, changes in the interior and surface of the earth, and the dynamic forces that cause those changes

What are the three main types of rocks, and the processes involved in their formation?

Igneous, sedimentary, and metamorphic

What are the basic types of silicate crystal structures?

Isolated tetrahedra, single chains, double chains, sheets, frameworks

How is geology related to other sciences?

It is a derivative science, it is a mixture of math, physics, and chemistry.

What are the limits and assumptions of science?

Limits -restricted to investigating natural world -seeks natural explanations for what we observe in our world -does not directly answer questions of ultimate reality -doesn't make moral or aesthetic judgements -does not tell you how to use scientific knowledge assumptions -there is a physical universe that can be explored by our senses -the physical universe is orderly -an additional assumption is needed: uniformitarianism

What variables control which minerals crystallize from magmas?

Magma composition, temperature, pressure

What is the origin of pyroclastic volcanic deposits? How are they classified? What is tephra? tuff?

Origin- deposition by airfall or flow classified by tephra or tuff tephra-unconsolidated deposits tuff- lithified ash deposits

What are the 8 most important rock-forming silicates? How and why are mafic silicates different from felsic silicates?

Quartz, plagioclase feldspar, potassium feldspar, muscovite mica are all felsic (light colored) Olivine, pyroxene, amphibole, and biotite mica are all mafic (dark colored)

What is the basic building block of the silicate minerals?

Silica tertrahedron, (SiO4)^4-

What is the difference between pahoehoe and aa lava? Be able to identify each from images of lava flows.

The pahoehoe flow has a comparatively smooth or "ropy" surface. The surface of the aa flow consists of free chunks of very angular pieces of lava

How does a mineral's crystal structure affect its (a) external morphology, and (b) physical properties?

a) controls external symmetry b) affects hardness

What is a rock?

an aggregate of minerals and/or a mass of glass

What are 5 important rock-forming non-silicates?

calcite, gypsum, halite, hematite, magnetite

What are the three main categories of sedimentary rocks and how are they formed?

clastic-by sedimentation of detrital particles chemical- precipitation of dissolved ions directly from water biochemical- material made by organisms

What is foliation, and what does it tell you about pressure conditions during metamorphism? What are some consequences of foliated rocks for roads and dams?

foliation: planar alignment of platy minerals(results in layered rock)

Texturally and mineralogically, what happens to shale protoliths during progressive stages of metamorphism?

goes from slate to phyllite to schist with added temperature

How are intrusive and extrusive igneous rocks different in terms of their texture (grain size)?

intrusive rocks have phaneritic (large) grain size and extrusive rocks are aphanitic (smaller) grain size

What is a geotherm?

line or surface within or on the earth connecting points of equal temperature

What are polymorphs?

minerals sharing the same chemical composition but having different crystal structures

What are the various components of magma? (i.e., magma can contain more than just melt)

molten rock material (melt), dissolved gasses, exsolved gas bubbles, suspended crystals, suspended rock fragments (xenoliths)

What is uniformitarianism? What is it not?

natural processes operating in the past are the same as those that can be observed operating in the present. "the present is the key to the past" does not necessarily men that rates of natural processes have always been constant

What effects (in terms of textural and mineralogical changes) result from subjecting a rock to increased temperature? pressure?

recrystallization, growth of new minerals, deformation -foliation: planar alignment of platy minerals(results in layered rock) -lineation: linear alignments of elongated minerals

What are some common minerals found exclusively in metamorphic rocks?

slate, phyllite, schist, gneiss

How are rounding, sorting, and mineral content in sedimentary rocks related to the duration and distance of weathering/transport? For example, which has seen more weathering/transport: a poorly-rounded sandstone or a well-rounded sandstone? a sedimentary rock with a fair amount of feldspar and biotite in it, or a sandstone primarily composed of quartz?

the farther the transport the more rounded, sorted, and less mineral content

What is meant by the term "protolith"?

the original rock before an metamorphism