Laboratory Manual for Introductory Geology 4e

drainage patterns occur where there are concentric rings of alternating resistant and
nonresistant rocks—typically found in structures called domes and basins. Parallel
drainage patterns occur on a uniform slope where several streams with parallel
courses develop simultaneously.
EXERCISE 13.4
Drainage Basins and Drainage Divides
Name:
Course:
Section:
Date:
FIGURE 13.15 is a map showing several tributaries on the north and south sides of the Missouri River near Jefferson City,
Missouri. One large tributary, the Osage River, joins the Missouri from the south, near the eastern margin of the map, but
most of the tributaries on the north side are much smaller.
(a) With a colored pencil, trace one of the tributary streams feeding directly into the Missouri River from the north. With
the same pencil, trace the tributaries that flow directly into that stream, and then the tributaries of those smaller
streams. Remember the “rule of V” (see Chapter 9) as you trace the smaller streams to their headwaters. As an
example, a segment of one small stream has been traced in red on the map.
(b) With a different colored pencil, trace an adjacent tributary of the Missouri, and trace its tributaries in turn. Repeat for
more streams and their tributaries on the north side of the Missouri River, using a different color for each stream.
(c) You have just outlined most of the drainage on the north side of the Missouri. Now, again with a different colored
pencil, trace the divides that separate the individual drainage basins for each master stream. This should be easy
because you’ve already identified streams in each drainage basin with a different color. An example of this step has
been done in blue for the stream segment traced in red on the map.
Note that some drainage divides are defined sharply by narrow ridges, but others that lie within broad upland areas, where
most of the headwaters are located, are more difficult to trace.
EXERCISE 13.5
Recognizing Drainage Patterns
Name:
Course:
Section:
Date:
(a) What drainage pattern is associated with the Mississippi River drainage basin in Figure 13.13? What does that tell you
about the materials that underlie the central part of the United States?
(b) What drainage patterns are associated with the areas shown in Figures 13.19 and 13.20 (ignoring the Susquehanna
River in Figure 13.20)? What do these patterns indicate about the rocks underlying those areas?
344 CHAPTER 13 LANDSCAPES FORMED BY STREAMS