The absolute age of a rock is expressed with

Activity 8.1B- Questions 1, 3, & 4 (Page 217)

The picture below is an outcrop about 5 meters thick near Sedona, Arizona. The red rock is an ancient body of soil. The brown layer in which grass is rooted is modern soil. The blocky brown-gray rock with wide fractures (cracks) is an ancient lava flow (basalt, a volcanic rock). This outcrop is a natural geologic cross section of rock layers, analogous to the cake.

1. Which layer is the oldest? How do you know?

3. Notice the fractures (cracks) that cut across the lava flow layer. Are they older or younger than the lava flow? How do you know?

4. Notice that clasts (broken pieces) of the lava flow are included in the brown soil. Are they older or younger than the brown soil? How do you know?

Activity 8.1C –Question 1 no need to submit the figure to show your tracing of the contacts (Page 218)

1. Using a pen, trace two of the contacts between layers of the red sandstone as well as you can. Assuming that the red sandstone layers were originally horizontal, what may have caused them to be folded in this way?

Activity 8.3A - (Page 221)

A. Analyze this fossiliferous rock from New York.

Figure 8.10

1. What index fossils from Figure 8.10 are present?

2. Based on the overlap of range zones for these index fossils what is the relative age of the rock (expressed as the early, middle, or late part of one or more periods of time)?

3. Using Figure 8.10, what is the absolute age of the rock in Ma (millions of years old/ago), as a range from oldest to youngest?

Activity 8.5A (Page 223)

A. Refer to the image below, an outcrop in a surface mine (coal strip mine) in northern New Mexico. Note the sill, sedimentary rocks, fault, places where a fossil leaf was found, and isotope data for zircon crystals in the sill.

1. What is the relative age of the sedimentary rocks in this rock exposure? Explain your reasoning.

2. What is the absolute age of the sill? Show how you calculated the answer.

3. Locate the fault. How much displacement has occurred along this fault? ______meters