Objectives:

Upon completion of this unit students should be able to: Describe the major types of sediment gravity flows Relate sediment gravity flows to liquid content, forces that keep grains aloft, and transport mechanism Give examples of types of sediment gravity flows Discuss the Normark/Walker fan model. List the beds that form in an idealized Bouma sequence. Show how deep sea fans typically prograde outward, and draw a stratigraphic column that represents a typical deep sea fan.

Reading Assignments:

Please include the field trip guide in this week's reading assignment!  Answer at least one question about the field trip on your reading log.   Lecture 8: Mass movements, sediment gravity flows - Boggs, 5th edition, pp. 31-33, 38-41.   Lecture 9: Deep sea fans and deep marine deposits - Boggs, 5th edition, pp. 33-38, 292-305.   Fill out a reading log for this week's reading assignment.  The reading log will be due at the beginning of class on Wednesday. Reading log

 

Field trip:

Our weekend field trips will leave at 7:00 Saturday morning and 7:00 Sunday morning.  Meet at the parking garage near the football stadium (Parking structure 3).  Be prepared for a long day in the field.   Bring these things:   extra water pencils extra snacks eraser hat clip board rain gear if necessary Brunton compass field notebook first aid kit rock hammer sunscreen, t.p. hand lens A really, really good attitude! We will be away from the vehicles for several hours, and will hike along a stream bed.  The hike will be across large boulders and uneven surfaces.  If you think this may be problem please talk to me ahead of time, and we will make reasonable accommodations. I will give you a copy of the field trip guide in class.  If you need another copy click here:   Cache Creek Field trip   Field trip assignment   Produce a drafted stratigraphic column from the section you measured at Cache Creek.  Use the guidelines from your field trip handout. Many students will measure and draw at least 25 m. of stratigraphic section.  If you work slowly you should do detailed work rather than fast and sloppy work.    Due date:  In lab, March 12th or March 14th   Help sessions:  5:30 Monday March 5th, 5:30 Wednesday March 7th.  Bring a laptop if you have one!

 

Class notes:

Lecture 8 notes Lecture 9 notes

 

Graphics from lectures:

Lecture 8 graphics Lecture 9 graphics

Lab: Sandstone I.D.

In lab this week we will practice identifying and classifying sandstones.  I will show examples of feldspar-rich, quartz-rich and lithic-rich sandstones, and you will describe an unknown sample for homework.   Samples to look at during lab (samples will be kept on display through next week):   Quartz arenite Sample QA: Clean quartz arenite Sample 8: Quartz arenite with iron stain (cement)   Arkose: feldsarenite or feldspathic wacke Sample FA: has orthoclase and plagioclase Sample D: has abundant PRF's Sample PGS: high feldspar content, but also high matrix content and abundant PRF's   Lithic-rich, wacke Sample 12: lots of VRF's Sample 3: dark-colored VRF's (may be basalt?), abundant feldspar Sample LW: lithic clasts, high matrix content   Unknown sample for homework:   Describe and name the unknown sandstone using Folk and Gilbert's classification systems.  Include these sections:   Observations: General observations first:  rock name, sorting, % grains, matrix and cement (these should add up to 100%), induration (this related to cementation, and describes how well the grains are held together) and porosity, if you are able to make an estimate.   Specific observations next: Use a table to show % composition, size range, roundness, color, other important features of each grain type.  Refer to the table before you present it!  Note:  grain composition (percentages) should also add up to 100%.   Round off estimates to the nearest 10%. The table should have these columns:   Composition Percent Size range Roundness Color Other                                                               Interpretations:   Finish with a short paragraph of interpretations about the unknown sand.  Identify interpretations with a heading so they stand apart from your observations.  Discuss the textural maturity of the sandstone.  Use sorting, grain size, matrix content and grain texture (polish, frosting, etc) to justify your answer.  Discuss the compositional maturity of the sandstone.  Use the presence of soft or resistant grains to justify your answer.  How far did the grains travel before deposition? Can you tell anything about the source for the unknown sandstone?  What types of material were present in the source area? Can you identify the environment or agent of deposition?  Support your answer with information about the sorting or texture of the sample. Answer key for unknown sandstone #1