Answer Happy

15. Why does Unit D contain Jugus sodai at Section 6, although it contains both Jugus sodai and Bottleus gado- raderei at Section 2? 16. You have proven that Rock Units Y and S are the same age at Unit D. Why was the sand deposited at Unit S, while silt and marl were deposited at Unit Y? 17. Although Valvata sp. and Unio sp. have long ranges and are not useful for age determination, what infor- mation can they tell us about the environmental interpretation of the area? 18. Why is Unit D much thicker than Unit Y, even though it was deposited at the same time? 19. Was the lake present when Rock Unit Q was deposited? Explain your reasoning.
5 0 10 m Unit Sand and gravel Sandy peat Cross-bedded sand Ripple-marked sand D SECTION 6 Peat Cross-bedded sand SECTION 4 Sand and gravel 0.5 Bandy pear Cross-bedded, sand SECTION 2 Shale 1.0 km Peat Cross-bedded sand SECTION 3 Unit Limy shale Unit P Poat Cross-bedded sand Unit G SECTION 1 brewen 8 bison P. columbi FIGURE 6.5 Stratigraphic section at the locations shown in Figure 6.6. firewateri Unit S Ripple-marked t sand Poat SECTION S FIGURE 6.6 Stratigraphic diagram along the line of sections 6, 2, 1, and 5 of Figure 6.5. Rock units D, Y, and S are a time-rock unit. Units P, Q, and G are both rock units and time-rock units.