Lab. 7 Stratigraphy and Lithologic Correlation 1. a. Draw lines between the three stratigraphic sections below to connect the geologic contacts between similar lithologies. (USE A RULER!!.) Note that each vertical column is a stratigraphic section. Each lithologic unit can be regarded as a bed. b. How many beds can be correlated across all three sections? 1 c. How thick is the thickest stratigraphic section (or column of rocks)? d. A bed of coal is present in sections B and C. How deep would you have to drill in section A (starting at the top of the section, up near the letter A) to reach the buried coal seam? ====================================== 2. a. Draw lines to correlate the two sections below. 2 b. Which section (A or B) contains an unconformity? c. Which units are missing from that section because of the unconformity? d. Label the position of the unconformity with an arrow and the word "unconformity". e. What type of unconformity is it? ===================================================== 3. a. Draw correlation lines between the three sections below. Note that the units vary in thickness in each section. b. What happens to the conglomerate in section C? Why is it not 3 present in section A or B? c. Why does the thickness of the sandstone change from section A to section B? d. In which direction (west or east?) was the land? e. In which direction (west or east?) was deeper water? f. Label the right side of section C with arrows to illustrate transgresion (T) and regression (R). ===================================== 4 4. a. Correlate the three sections below. (Note that the limestone unit is present only in sections A and B, and that it is much thinner in section B. It has thinned to the point where it is not present at all in section C.) This is called a pinchout. b. What type of sequence (transgressive? regressive? or transgressive-regressive?) is represented here, as indicated by the vertical sequence of facies? 5 c. Label the column on the left with up-pointing arrows to indicate the part of the sequence which represents a transgression (T), and the part which represents a regression (R). Label the arrows T or R. d. These sediments were deposited in an ancient sea. Based on the rock types, which facies (not section) was deposited nearest to the mainland? e. Which facies (not section) was deposited farthest from the land? f. In which direction (west or east) was the land? 6
