Geology Lab Practical
what three geological observations did darwin make in his travels?
- formation of volcanos - rising of the andes by earthquakes -fossil relatives of modern species
what does the term metamorphic grade refer to?
-age of a metamorphic rock -the degree to which a metamorphic rock's protholith has changed - whether a metamorphic rock has an igneous or sedimentary protholith
the presence of water_______
-lowers the melting temp during flux melting -helps the magma rise towards the surface -causes explosive volcanic eruptions
3 observable properties of a mineral
-luster -hardness -odor
what must be true in order for an ore mineral occurrence to be economically valuable?
-natural processes must have concentrated the desired element to greater degree than its avg crustal abundance -there must be enough of the ore mineral to make extraction profitable -the sale price of the element must be greater than the costs of mining and extraction
3 characteristics of a mineral
-naturally occurring -solid -chemical composition
at which location is volcanic activity abundant?
-oceanic ridges - subduction zones
where does most of the earth's volcanic and earthquake activity occur?
at the edges of the lithosphere plates and at hotspots
intrusion of granite into layers of sedimentary rock would cause
contact metamorphism
in the plate tectonic model, where is large scale compressional stress found?
convergent plate boundaries
mohs hardness scale describes the relative hardness of a mineral not absolute hardness, this means that:
diamond will scratch talc but talc cant scratch a diamond
the latitude of a location is based on the
equator
metamorphic rocks can be made from what parent rocks?
igneous sedimentary metamorphic
what does earth's magnetic field generate?
lines of force that parallel the earth's surface at the equator
where does new lithosphere form? and where is it consumed?
midocean ridges; subduction zones
what is true of a clastic sedimentary rock?
minerals crystallize from molten materials
direction of 315 degrees in the azimuth system corresponds to ...
northwest
well rounded grains in a clastic sedimentary rock indicate?
numerous collisions between particles during extensive transportation
in an anticline, the ______ rocks are exposed in the center of the fold, and bed typically dip ______ from one another
oldest; toward
the longitude of a location is based on the
prime meridian
grain size of an igneous rock is determined by
rate of cooling
collision of two continental plates would cause
regional metamorphism
what changes take places during physical weathering?
rocks are broken into smaller pieces
difference between sill and dikes
sills are parallel to layering in surrounding rocks while dikes cut across them
the texture of a rock includes the ________________ of its constituent grains
size, shape, and orientation
Earth's surface was primarily formed from _____________ events
slow occurring
igneous rocks form by:
solidification of magma at the surface or within the earth
where are intermediate igneous rocks most commonly found?
subduction zones
the presence of footprints in a sedimentary rock is compatible with origin in all of the following environments except:
the floor of the atlantic ocean
foliation and lineation are terms that describe:
the orientation of mineral in metamorphic rocks
where is large scale tensional stress found?
transform faults
cross bedding and ripple marks are the result of ______ during depostion
water or wind currents
in a syncline, the ______ rocks are exposed in the center of the fold, and bed typically dip ____ from one another
youngest; away from