Geology 201 – Assignment 3

This assignment includes a number of short-answer questions plus one essay and one lab exercise. 

 

Part A – questions (20 points in total)

(Please answer each of these in a few words.  Point-form is OK.)

 1) In your own words, define the concept of facies change, and give an example of a depositional environment in which a facies change is likely to exist.  (Note: The text does not give a very clear definition of facies change.  For a simple definition, try:  http://gpc.edu/~pgore/geology/geo102/facies.htm) (2 points)

 2) The following vertical sedimentary sequences have been defined.  For each one indicate whether it is the result of a transgressive or a regressive sequence, and briefly describe the depositional environment. (4 points) 

A

B

i) biomicrite interbedded with evaporite

ii) oosparite

iii) biosparite reef deposits

iv) calcareous shale

 

i) mudstone with sandstone beds (TBCDE)

ii) thick TAB  sandstone beds

iii) pebbly conglomerate channels (TA)

iv) coal-bearing sandstone

 

 3) The four main types of unconformities are:  angular unconformity, nonconformity, disconformity and paraunconformity.  Briefly describe each of these - in your own words, and summarize the main geological events that would be necessary to produce them. (4 points)  

4) Explain why ecological variations are a significant problem for the application of paleontology to dating rocks. (2 points)

5) Draw cross-section diagrams showing the plate-tectonic settings and any other relevant tectonic features of the following types of basins (8 points):

  

Part B - Essay

Complete the assigned reading from the William Smith book, and prepare an essay (up to two pages) as outlined on the web site.  Point-form is acceptable. (20 points)

  

Part C  Lab

Complete a stratigraphic section measurement and description on an outcrop of your choice following the procedures that we used on the Parkway outcrop near to Harewood Mines Rd.  Your section should extend over at least 3 m stratigraphically, and should have at least  three recognizably different units.  

Please, please, please talk to me before you make a final decision on where to do this.  I would be more than happy to visit the site with you and give you some advice as to how to get started.

Using one or more of the stratigraphic section forms, make a description of the units that you have identified, focusing on lithology (grain size, sorting, grain type if visible, rock name), colour and weathering effects, sedimentary structures (eg. graded bedding, cross-bedding).  Note any relationships between units, such as disconformities, unconformities, scouring etc.  Make some suggestions about the depositional environments for the various units. 

Draw a stratigraphic log at a vertical scale of 1 cm = 20 cm.  Use the type of notation that we used for the Parkway exercise (as is described in Box 15.1 of P&S).  If you need a form for drawing the log, try this one.