Geology Lab Final
15' Maps Graphic Scale
1" = 1 mile
Three Frequently used methods for designating location are
1) Latitude and Longitude 2) Public Land Survey 3) In reference to propionate features
15' Maps Fractional Scale
1:62,500
Section
36 one mile square parcels of land each with 640 acres
3. Contour line never
Branches or Splits
Total Relief
Difference between the hightest and lowest points on a map
Contor lines widely spaces apart indicate?
Gradual Slope
General Rules For Contor Lines
In order to create uniformity between various map publishers, contor lines must conform to certain guidelies
Public Land Survey Example
Northwest 1/4 of the Southeast 1/4 of section 27 T2S R2W
Public Land Survey
Provides a precise method for identifying the location of land, based on a grid system.
R2W means
Second range west of the prime meridian
T2S means
Second township south of the Baseline
Topography means
Shape of the Land
Close together contor lines represent what?
Steep Slope
Township
The six square mile area descrived as being north or south of the baseline
Quadrangles
Two dimensional representations of the three dimensional surface of Earth
Where is the name of a topographic map usually found
Upper right hand corner
Sycline fold
Youngest bed in the middle Plunges towards limbs
When contour lines cross stream valleys or dry stream channels they form
a V that points upstream
A concentric series of closed contours with hachure marks represents
a closed depression
Hills are represented by
a concentric series of closed contour lines
Graphic Scales
aka Bar Scales. are a series of bars divided in to segments that show the relation between measurements on the map to the actual distance on earth.
Fractional Scales
aka Ratio Scales expresses a distance of one unit on the map, represents some distance of the same unit n the surface of the earth
Contor lines never cross except to show
an overhanging or vertical cliff
footwall block
belown the fault plane
Steep slopes are shown by Gentle slopes are shown by
closely spaced contours; widely spaced contours
Dome
concentric geologic structures with all rock layers dipping outward from a central point oldest exposed rock in the center
Basins
concentric geologic structutes with all rock layers dipping inward with the yougest exposed rocks at the central point
If rock type is homogenous the drainage pattern is
dendri c
Relief
difference in elevation between two points on a map
Topographic maps published by the USGS are contoured in
feet or meters usually referenced to sea level
reverse fault
hanging wall moved up in reference to footwall
normal fault
hanging wall moves down in reference to gravity
hanging wall bock
is always aboutve the fault plane
Contor Lines
line drawn on a toppographic map that connects all that have equal elevation above or below a datum
downstream the valley is said to become more
mature
Sinousity
measure of how winding the course of a stream is
number one is the oldest or younges rock layer
oldest
Anticlene fold
oldest bed in the middle plunges towards nose
Footwall block
on left
hanging wall
on right
Contour lines that occur on opposite sides of a valley or hill always occur in
pairs. Single contour lines do not lay between maximum ridge and minimum valley contour lines
1. Contour lines connect
points of equal elevation
2. Contour lines seperate all points of higher elevation from
points of lower elevation
Ranges
provide the eastern and western edges of the township and are descrived as veing east or west of the principal meridian
streams may radiate from a central point
radial
follow reguarly fractured rock
rectangular
datum
reference plane on the earths surface
Tor report a reversal of slope you must
repeat elevations
dendritic
resembles a tree shape
Townships
six square mile areas
stream gradient
steepness of the slope
what is the most common landform on the earths surface
stream valleys
trellis
streams mostly follow the valleys but can cut through the ridges
A stream valley is
the region directley and indirectly eroded by the stream
Discharge rate
the total volume of water passing a certain point
linear ridges and valleys develop a pattern of
trellis
Cut bank
water velocity and turbulence are greater and the abrasive energy of the water and suspended sediments erodes the stream bank.
Point bar
water velocity is less and allows for sand or gravel to be deposited in the point bar
downcutting
which deepens the channel toward the base level
headward erosin
which extends the head of the vally upslope
lateral erosion
which widens the stream valley
the v-shaped part is reffered to as
youthful