Geology 103 (Sedimentology and Stratigraphy)


California State University, Sacramento


Week 6: Mass movements and sediment gravity flows,

Deep sea fans


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:

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 each Wednesday.

Reading log


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)



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 (sample MRF).  Put your description in paragraph form.  Include the rock name, sorting, composition, roundness, size range, color, cement and any other important features, Describe the rock first, then make interpretations about the environment and agent of deposition.