Geol 5, Lab #9: The Advance and Retreat of Ancient Shorelines (Access is reserved to Cal State LA students only)

PALEOGEOGRAPHY

question 1, page 89

Your line should be close to the zero western line, passing between the "t" (terrestrial) and "m" (marine) symbols. That would be the approximate edge of the sea that covered much of North America during the Late Cretaceous

question 2, left column, page 90

You should look for coastal, transitional facies, or even continental facies; for instance, sandstones (either quartz sandstones or arkoses) and conglomerates, coal beds; fossils of land plants and animals, possibly of shallow marine organisms. Your sequence cannot end in the middle of the depositional basin.

question 3, page 90

It was the source of the sediments filling up this Late Cretaceous basin. The presence of conglomerate suggests a mountain chain

question 4, page 90

question 5, page 90

question 6, page 90

question 7, page 91

The western zero line in Fig, 9.2 represents the border of a region in which Lower Silurian rocks have been deposited but have ben lost to erosion. The reason is that you cannot have pelagic limestones at the edge of a depositional basin.

TRANSGRESSION AND REGRESSION OF THE SEA

question 1, page 92, top left column

yes
each lithofacies is characteristically distinct, in terms of lithology, from the others

question 2, page 92, left column

no
you can trace the vertical sequence by matching it horizontally and observing that the same formation was deposited at different times in different places (Walther's Law)

question 3, page 92, left column

question 4, page 92, left column

in case of a regression, the sequence is reversed: from bottom to top, limestone, shale, sandstone

SHORELINES OF CAMBRIAN TIME

question 1, page 92, bottom left column

question 2, page 92, right column

The sea transgressed
You can notice in the paleogeographic maps of Fig. 9.4 that coarser facies were covered by fine facies (sandstone by shale, and shale by carbonate), thus indicating a rise in sea level
Late Cambrian

question 3, page 92, right column

The presence of quartz sandstone around areas where there is no record, indicating that these were islands surrounded by a beach.

question 4, page 93

question 5, page 93

Draw the contact (exactly below the last layer at the bottom of the pile) [this was skipped because of lack of clarity]
A non-conformity

ANCIENT SHORELINES IN THE BOOK CLIFFS OF UTAH

question 1, parts I, II, and III, page 84

question 2, parts I and II, pages 84 and 86

As the sea regressed only
The coal is always found on top of the sandstone, never at the bottom
The shoreline retreated (moved towards the ocean)
Again, the beach would be covered by non marine swamp deposit, that forms more inland from a beach

question 3, page 94

question 4, page 94