Geology Reference
In-Depth Information
204
III. Introduction to Water Resources and Contamination
FIGURE 12.6
Map showing well locations near Darcyville, for completion of topographic and geologic maps. The 260-foot contour
line is given.
the diagram (the line for well 1 is given). Mark the land
elevation at the top of each well on this line with a short
bar and label the elevation. Obtain the land elevation
value for each well from Table 12.2.
d.
Now complete the
geologic cross sections.
Look at the
labeled geologic units in each well. Draw lines between
wells to connect the same contacts separating geologic
units. Not all units can be connected because some units
may not occur in adjacent wells. Such units must "pinch
out" before reaching an adjacent well when you construct
your cross section.
Note: Optional: You could check agreement between
your profile and a profile made from the topographic
map constructed in Question 4, but this is optional. The
points on profile y-y' between wells were obtained from
the contour map.
8.
Where is the best location to drill a water well for a house
(domestic use well)? Briefly explain your choice based on the
cross sections and geologic map that you constructed.
b.
Add the stratigraphy for each well (wells 2-4 and 5-8).
Starting from the topographic profile, place a tick mark
on the vertical line for each well corresponding to the
elevations where the geologic units change (i.e., the con-
tacts of the units). The contacts for well 1 are entered on
Figure 12.7.
9.
Assuming that all wells obtain water from every sand or
gravel unit they intersect, which wells have the greatest
potential for pollution from a nearby spill of toxic liquids?
Explain your choices on the basis of the geology in your
cross sections (Figure 12.7).
c.
Label each layer of each well as done for well 1.
