101 Geology Sec. 1&2 Geologic Time/Structures Homework 15 points
Name ______________________ WSU ID ____________________
Due before lecture begins on Friday March 11. Homework turned in after the bell rings will lose points: late penalty of 50% after class and each day there after. Homework on a separate sheet of paper will not be accepted for this assignment. Point values for individual questions are listed in (). Use the key of rock patterns to determine rock types. KEY Rock Patterns
(Colors may vary)
Hint: There is a relative age dating help document on the course web page for you to review. www.wsu.edu/~geology101 or www.wsu.edu/~geology101/sec1 On a separate piece of paper first determine the complete order of events from oldest (bottom) to youngest (top) before you label the events below. There may be more than one correct answer.
PROBLEM #1 Cross-Section a) Label the following events from oldest (1) to youngest (7). (3.5 pts) ___ Ocean rose or land subsides - deposition of bed C forming an unconformity(uc-2). ___ Deposition of beds F& H ___ Uplift and erosion of bed H ___ Uplift and erosion of bed K, L & intrusion Z ___ Intrusion Z ___ Tilting of beds F, H, L, K ___ Oceans rose or land subsides - deposition of bed L&K forming an unconformity (uc-1)
uc-2 K
A
C L H
uc-1 Fault B Intrusion Z
F
b) Unconformities exist between sedimentary beds L and H and again between beds C, K and L. In addition, the unconformity types change as you move away from the intrusion. The type of unconformity that exists between beds K and C is a ________________________ (0.5 pt). The type of unconformity that exists between beds H and L is a ___________________________(0.5pt). [hint - note orientation of units F, H, L and K] What type of unconformity directly exists above the intrusion Z at point A)? _____________________(0.5 pt). c) Given: Intrusion Z contains radioactive isotopes with a known half-life of 55,000,000 years. How old (in years) is intrusion Q if 12.5% of the parent isotope remains? Show work and include units for full credit.(1pt)
d) Using the absolute age you calculated in c), in which geologic time Era and Period was intrusion Q formed? Era: _______________________________ Period: ____________________________________ (Refer to Geologic Time Scale on page 265 in your lecture text.) (1 pt) PROBLEM #2 Cross-Section a) Label the following events from oldest (1) to youngest (6). (3 pts) ___ Intrusion L & W ___ Intrusion Y ___ Deposition of sedimentary units F, E, D, C, B, A ___ Fault 1 ___ Fault 2 ___ Uplift tilting and erosion forming present day erosion surface b) What type of fault (specify type) is fault 1? _________________ (0.5 pt) c) What type of stress is associated with fault 1? ____________________ (0.5 pt) d) What type of fault (specify type) is fault 2? ...