Aeolian and Lacustrine Sedimentation Warm-Up

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Essay Question

One of the big arguments in sedimentology during the past few decades is whether certain ancient sandstone deposits were formed in deserts as aeolian dunes, or in submarine settings as subaqueous dunes. How would you tell aeolian from subaqueous dunes? You may wish to use the Navajo sandstone as an example in your discussion.

Multiple Choice Question

Which of the following can be used to distinguish lacustrine from marine deposits?

lacustrine deposits commonly have well-developed tidal sequences

marine deposits often display varves which are the result of seasonal changes in the marine regime

facies patterns always differ in scale, consequently lacustrine facies will be on a smaller scale than marine facies

turbidites are confined to deep marine sequences

chemical sediments do not form in lakes, so when you fine chemical sediments, you know you have a marine environment

algal structures in sediment are confined to marine sequences

True or false? Seasonal variation in density stratification versus convective overturn often results in the development of a well-developed, rhythmic lamination in lacustrine sediments. These laminations can provide a measure of time in the stratigraphic record.

true

false