Geology Reference
In-Depth Information
TABLE 12.2 Darcyville Well Logs. All measurements
are in feet. Material is the type of geologic deposits
(sediments). Thickness records how many feet of a
particular unit were encountered when the well was
drilled. Depth is how far down it is from the surface
to the bottom contact of the specific type of geologic
deposit.
Elevation is the height above sea level for
the bottom of the geologic deposit.
Data for wells 1, 2
and 3 are filled in. Till is a poorly sorted silt and clay-
rich sediment deposited by a glacier.
Well 6; Darcyville (land elev. 290)
Material
Thickness
Depth
Elevation
till
70
fine sand
15
till
25
clay
4
Well 7; Darcyville (land elev. 265)
Well 1; Darcyville (land elev. 265)
Material
Thickness
Depth
Elevation
Material
Depth
Thickness
Elevation
coarse gravel
15
coarse gravel
40
40
225
till
35
till
45
85
180
fine sand
10
clay
10
95
170
25
till
clay
15
Well 2; Darcyville (land elev. 275)
Material
Thickness
Depth
Elevation
Well 8; Darcyville (land elev. 255)
till
15
15
260
Material
Thickness
Depth
Elevation
coarse gravel
25
40
235
coarse gravel
40
till
15
55
220
till
35
fine sand
10
65
210
clay
10
till
30
95
180
clay
25
120
155
5. On Figure 12.6, beside each well, place the name of the
material that is found at the land surface. These materials are
those found in the top unit for each well.
Well 3; Darcyville (land elev. 290)
Material
Thickness
Depth
Elevation
till
60
60
230
fine sand
25
85
205
till
25
110
180
6.
Make a
geologic map
of the area in Figure 12.6 by interpret-
ing the distribution of sediment (material) types and group-
ing any areas with similar materials. Do this by drawing a
line to show the approximate contact between any two dif-
ferent materials at the surface. Without knowing the exact
location of contacts, there will be more than one way to show
the extent of materials. Your geologic map provides the dis-
tribution of sediments at the surface in this map area.
clay
25
135
155
Well 4; Darcyville (land elev. 305)
Material
Thickness
Depth
Elevation
coarse gravel
45
till
20
fine sand
45
till
15
clay
10
7. Draw two
geologic cross sections
(x to x', and y to y', for the
map on Figure 12.6). The first cross section is through wells
1, 2, 3, and 4 (x-x'). The second cross section is through
wells 5, 6, 7, and 8 (y-y'). Construct the cross sections on
Figure 12.7 following the instructions below.
Well 5; Darcyville (land elev. 310)
Material
Thickness
Depth
Elevation
coarse gravel
15
till
40
medium sand
40
till
35
a.
Draw the
profile
of the land surface; the profile for
y-y' is given as an example. On the upper diagram in
Figure 12.7 at the locations of the wells on the lower axis,
draw a light line vertically above each well to the top of
clay
10
