Common Minerals and Rocks

Olivine

Granite is usually comprised of three minerals in varying amounts.  They are hornblende, feldspar, and quartz.  Hornblende is black. It can fracture on the plane and produce small shiny surfaces.  Feldspar is usually pink.  Quartz may come in translucent or rose.  It has a crystalline structure. Some other minerals include olivine which is formed deep within the earth under great pressure.  It is green in color and may also occur in granite.

Hornblende

Feldspar

Quartz

Isarithmic Map - Mean Annual Precipitation in Georgia

Types of Maps

There are many types of maps. they all require marginal data and possibly a legend to maximize their usefulness.  Below are some common types of maps.

Isarithmic maps, also called contour maps, identify areas of smooth, continuous, univariant data and show the separation of such areas using isobars.  This one gives North Carolina's temperature on a given day.

Chlorpleth maps show aggregate statistical data for predefined areas such as counties or states by coloring or shading these regions.

Dot density maps use a single dot to represent a given quantity of the variable represented. All dots are the same size and represent equal quantities.  The more densely packed the dots are, the higher the quantity being represented.   This on identifies Public Safety installations.

Proportional symbol maps use a single symbol for a predefined area.  The symbol is sized proportionate to the quantity of the variable being measure.  This one illustrates wine consumption in Europe.

Prepared maps identify features of interest on a given landscape.  This one shows snowmobile trails in the Black Hills of South Dakota.

The Yellowstone Caldera & Plate Tectonics

  Yellowstone is one of the most fascinating geological features on Earth!  It is the largest volcanic caldera on the planet.  A caldera is a cauldron-like feature created by a collapsed supervolcano.  The caldera sits astride a geologic hotspot; an area of the earth's crust where hot, lightweight molten rock rises near the surface.  This phenomenon is responsible for "Old Faithful", other geothermal vents (geysers), and for other features like hot, bubbling mud pans.
     Yellowstone is actually comprised of three overlapping calderas. Plate tectonics accounts for its enormous size.  Over a long period of time, volcanic activity created the first caldera.  The hotspot remained in place as the plate with its caldera moved west.  The hotspot erupted again and eventually formed another caldera which, in turn, moved west with the plate.  The process continues today.  The area is monitored constantly because the threat of another supervolcanic event is ever-present.  Yellowstone experiences 1000-2000 measurable earthquakes every year.