The Following Questions Refer to the Description and Figure Below

question 72

Multiple Choice

The following questions refer to the description and figure below.
The figure represents a cross section of the sea floor through a mid-ocean rift valley, with alternating patches of black and white indicating sea floor with reversed magnetic polarities. At the arrow labeled "I" (the rift valley) , the igneous rock of the sea floor is so young that it can be accurately dated using carbon-14 dating. At the arrow labeled "III," however, the igneous rock is about 1 million years old, and potassium-40 dating is typically used to date such rocks. Note: The horizontal arrows indicate the direction of sea-floor spreading, away from the rift valley.

Figure 25.1
-Assuming that the rate of sea-floor spreading was constant during the 1-million-year period depicted above, what should be the approximate age of marine fossils found in undisturbed sedimentary rock immediately overlying the igneous rock at the arrow labeled "II"?

• A) 10,000 years
• B) 250,000 years
• C) 400,000 years
• D) 1,000,000 years

---

Definitions:

Cerebellum

A part of the brain at the back of the skull, which regulates movement, posture, and balance.

Traumatic Head Injury

Physical trauma to the head that can lead to various levels of brain injury, ranging from minor concussions to severe brain damage.

Corpora Quadrigemina

A structure in the midbrain consisting of four bodies, the superior and inferior colliculi, involved in visual and auditory processes.

Medulla Oblongata

The lower portion of the brainstem involved in autonomous functions such as breathing and blood pressure regulation.