Room 206 EWSC (7-2424)

OFFICE HOURS: M 10-11 am, T 2-3pm, W 11-12 am

TEXT BOOK: Tarbuck & Lutgens, EARTH: An Introduction to Physical           Geology, 6 th edition, Prentice-Hall.

LAB MANUAL: Busch, Laboratory Manual in Physical Geology, 5 th                edition, Prentice-Hall. 


     1. Your lab TA will give you assignments, quizzes and exams in lab and, based on your performance, will provide me with an overall numerical lab grade between 0 and 100 points. Twenty five percent of your lab grade will be based on a written lab report for a research project that will be described later.

     2. There will be a cumulative final lecture exam (multiple choice) during the finals period in December on which you can earn up to 100 points.

     3. There will be 3 to be announced exams (multiple choice) during the lecture classes, each worth 100 points. I will drop the worst of these three exams so that you can earn up to 200 points on your two best exams. There will be no makeups for these three exams so you will get a zero on any that you miss.

     4. Your total numerical grade will be the sum of items 1 through 3 so that if you are perfect you will end up with at most 400 points.

          a. You will get an A if you have at least 360 points or are in roughly the uppermost 10 percent of the class. I say "roughly" because I will look for gaps in the distribution of total scores at which to place boundaries between letter grades. I will also consider class attendance if you are a borderline case.

          b. You will get a B+ if you have between 340 and 360 points or are roughly in the next 10 percent of the class.

          c. You will get a B if you have between 320 and 340 points or are roughly in the next 10 percent of the class.  

          d. You will get a C+ if you have between 300 and 320 points or are roughly in the next 15 percent of the class.

          e. You will get a C if you have between 280 and 300 points or are roughly in the next 25 percent of the class.  

          f. You will get a D+ if you have between 260 and 280 points or are roughly in the next 15 percent of the class.

          g. You will get a D if you have between 240 and 260 points or are roughly in the next 10 percent of the class.

          h. You will get an F if you end up with less than 240 points and are in the last 5 percent of the class.



      Mandatory!!! If you miss an exam you will get a zero and will have to rely on your grades in the other quizzes. In other words there will be no make ups regardless of your excuse. With a class of this size I can not sort through all of the tales of woe that will inevitably arise. In addition if you are a borderline case as regards the letter grade criteria outlined above, attendance may be taken into account in assigning your final grade.




Date     Topic                                     Text Assignment


8-24     Introduction                                     Ch 1

8-29     Matter and Minerals                       Ch 2

8-31     Matter and Minerals                       Ch 2

9-5      Igneous Rocks                                   Ch 3

9-7      Volcanic and Plutonic Activity           Ch 4

9-12     Weathering and Soils                         Ch 5

9-14     Weathering and Soil (EXAM)            Ch 1-5

9-19     Sedimentary Rocks                           Ch 6

9-21     Metamorphic Rocks                          Ch 7

9-26     Geologic Time                                    Ch 8

9-28     Mass Wasting                                     Ch 9

10-3     Hydrologic Cycle and Rivers              Ch 10

10-5     Rivers                                                 Ch 10

10-10    Ground Water                                    Ch 11

10-12    Ground Water (EXAM)                    Ch 6-11

10-17    Fall Break, no classes

10-19    Glaciers and Glaciation                      Ch 12

10-24    Glaciers and Glaciation                      Ch 12 

10-26    Deserts and Aeolian Activity             Ch 13

10-31    Shorelines                                            Ch 14

11-2     Shorelines (EXAM)                              Ch 12-14

11-7     Election Day, no classes

11-9     Crustal deformation                              Ch 15

11-14    Earthquakes                                         Ch 16

11-16    Earth's Interior                                     Ch 17

11-21    Earth's Interior                                     Ch 17

11-28    Seafloor Spreading                               Ch 18

11-30    Plate Tectonics                                     Ch 19

12-5     Plate Tectonics                                      Ch 19

12-7     Mountain Building & Continental Evolution        Ch 20

12-11    Final Exam (2 pm)                                Ch 1-20




Week          Topic


Aug 28        Minerals

Sept 4        Igneous Rocks

Sept 11       Sedimentary Rocks

Sept 18       Metamorphic Rocks

Sept 25       Rock and Mineral Exam, Topographic Maps

Oct 2         Fluvial Landforms

Oct 9         Glacial Landforms

Oct 16        No Labs

Oct 23        Research Project Data Analysis

Oct 30        Desert, Shoreline and Karst Features

Nov 6         Folds and Faults

Nov 13        Geologic Maps

Nov 20        Labor Day and Election Day Make Ups for Monday and                      Tuesday Labs only

Nov 27        Geophysics

Dec 4         Final Lab Exam                                      



     Geologists and engineers have long been curious about the processes that govern river drainage networks. When viewed on maps stream networks show a branching pattern, similar to those exhibited by trees, with trunk streams and their smaller tributaries. In the 1960s Ronald Shreve hypothesized that stream networks are "topologically random". Note that he did not say topographically random. You are going to collect data from maps in the Thomas Cooper Map Library to test this hypothesis. You and your class mates will pool your data and then each of you will write a short report describing your results and conclusions. This exercise will hopefully give you an appreciation of the scientific method which involves the formulation of a hypothesis, the collection of data to test the hypothesis, the presentation and analysis of the results, and the drawing of conclusions from the results. It will also give you a feel for the use of mathematics and statistics in scientific research.

     Now let me define what is meant by topologically random. Here are some definitions that are illustrated on Figure 1 below. This figure shows an example of a stream network. Streams that have no tributaries are called external links. All other links receive drainage from two or more tributaries and are called internal links. Links are stream segments that connect junctions. The example network has five external links and four internal links. The total number of links is nine. In general the total number of links in a network is equal to two times the number of external links minus one (eg. 2*5-1=9). This rule holds as long as no more than two tributaries join at a junction.

     Shreve defined the link magnitude (LM) of a network as being equal to the number of external links. The LM of the example network is thus five. Shreve also defined rules for determining the topological structure of a network. This is done by taking an imaginary trip through the network. You start at the mouth of the basin and travel upstream noting whether you are on an internal or external link. When you get to a junction you must turn left. In your trip you count each link only once. When you get to the end of an external link you go back downstream to the first junction that still has links upstream that you have not yet traveled on. Applying these rules to the network on Figure 1 the sequence of links on the trip is IIIEEIEEE where "I" stands for an internal link and "E" stands for an external link. Note again that the total number links in this sequence is nine. This sequence is called the binary code for this network.

     Figure 2 shows two other networks that also have a link magnitude of five. Note that they have different binary codes. Thus the networks shown in Figures 1 and 2 all have the same link magnitude but have different binary codes. They are thus topologically distinct. It turns out that for networks with link magnitude equal to five there are 14 topologically  distinct possible networks. If you work at it you might be able to write out the binary code for each. Shreve hypothesized that in nature each topologically distinct network for a given link magnitude should have the same chance of occurring. Thus if we worked out the binary codes for a large number of link magnitude five networks there should be about 7.1 percent (1/14) of each topologically distinct type. For basins with a link magnitude of two there is only one topological possibility (ie. IEE). For link magnitude of three there are two topological possibilities (try working out their binary codes) so there should be about fifty percent of each. For link magnitude of four there are five possible topological varieties (again try working out their binary codes) so there should be twenty percent of each.

     Note that on Figure 1 there are two sub-networks with a link magnitude of two and one sub-network of link magnitude four. On Figure 2 there are sub-networks of two, three and four. Thus in general networks with link magnitudes greater than two have embedded within them sub-networks of lower link magnitude.

     Thus to test Shreve's topological randomness hypothesis you will do the following.

     1. Go to the Thomas Cooper Library which is only open 9-5 weekdays. Bring several pieces of tracing paper and a ruler with you because they will not allow you to check out maps.

     2. Pick a state at random. Ask the map librarian for the USGS topo index map for that state. Pick at random a 7.5' quadrangle    map from the index and ask the librarian to get it for you. Find a basin with a link magnitude of five on the quadrangle. If you can't find a link magnitude basin on the map, pick another quadrangle. In determining the link magnitude, only use stream links shown as solid or dashed blue lines on the map. Reject any network in which more than two tributaries join at a junction.

     3. Find and record the latitude and longitude of the mouth of the basin and the name of the trunk stream if any.

     4. Make a tracing of the network.

     5. Workout the binary codes of the link magnitude five network and all link magnitude three and four sub-networks.

     6. Make a copy of your work and turn it in to your lab TA on or before Friday, October 6. If you know what you are doing, this work should not take more than an hour or so.

     Your TA will then compile the data collected by the students in your lab and combine it with data from all of the other labs. This should give us a sample size of 100 to 150. The compiled data will be given to you during the labs the week of Oct 23 along with instructions for its analysis. You will also be given instructions regarding the format and content of your report.



     Shreve, R.L., 1967. Infinite topologically random channel networks. Journal of Geology, v.77, pp.397-414.

     Shreve, R.L., !974. Variation of mainstream length with basin area in river networks. Water Resources Research, v.10, pp. 1167-1177.        


These figures are available in two formats:  Word Document file and as a PDF file. 

Figures 1 and 2 PDF

Word Document file

You may also view and print these figures from the following two web pages:
Figure 2

Last Updated August 18, 2000 by Eric Tappa at
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