(e) During which geological period(s) were the following sediments deposited: (i
ID: 2013391 • Letter: #
Question
(e)During which geological period(s) were the following sediments deposited:
(i) the folded mudstone with fossil trilobites and (ii) the sandstone? Explain your reasoning. (A few sentences for each sediment.)
(f)
List the sequence of geological events that produced the geological relationships seen in the cross-section, starting with the oldest and ending with the youngest (i.e. erosion of present topography).
(g)
For any tectonic events that you identified in part (f), explain whether the cause was horizontal compression or horizontal stretching. (Two or three sentences.)
Explanation / Answer
These questions cannot be answered without the cross-section in question. However, the following rules should be helpful for at least f and g: 1. Principle of original horizontality: layers of sediment are deposited horizontally and flat. So if there's something that isn't horizontal and flat, then whatever event that caused this had to happen AFTER that layer(s) were deposited. 2. law of superposition: if something's on top, it must have happened after what's underneath it. (This works in conjunction with original horizontality; if the rock has been folded over, it's not going to hold true.) 3. cross-cutting relationships: if you have a rock intruding into another, the intruding rock must have occurred after the intruded rock. (can you push a knife into a loaf of bread that hasn't been baked yet? of course not.) Also, any layer that cuts across another must be younger (happened after.) 4. If there is a fault in any layer(s), then the fault must have broken the layer(s) after the layer(s) were deposited. 5. principle of faunal succession states that the age of fossils in sedimentary rock mus follow the age of the rock, so (in general) fossils in layers above others will be younger than deeper fossils. hope this helps!
Related Questions
Navigate
Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.