In your textbook, read about magnetism. Use each of the terms below just once to complete the passage. isochron magnetic field normal-polarity older reversed-polarity younger Earth's (17) __ Iclhas changed over time A field with the same orientation as today's field is said to have (18) __ . A field that is opposite the present field has (19) __ Hy Magnetometers have been used to measure the ocean floor's magnetic field. Magnetic data of the ocean floor has been used to generate (20) __ maps, which have shown that the ocean floor is (21) __ near ocean ridges and (22) __ near deep-sea trenches. In your textbook, read about ocean rocks and sediments, magnetism, and seafloor spreading. For each item in Column A, write the letter of the matching item in Column B. Column B a. isochron b iron b. geomagnetic time crust ometer Column A 23. Device that can detect small changes in magnetic fields __ 24. Minerals containing this act like small needles and record the orientation of Earth's magnetic field at the time of their formation __ basalt flows constructed from data gathered from continental __ This type of line connects points on a map that have the same age in and formation __ Each cycle of specifis if and

## Step 1<br />The first blank in the passage is about the changing orientation of Earth's magnetic field over time. The term that fits this context is "normal-polarity".<br /><br />## Step 2<br />The second blank is about a field with the same orientation as today's field. This is referred to as "normal-polarity".<br /><br />## Step 3<br />The third blank is about a field that is opposite to the present field. This is referred to as "reversed-polarity".<br /><br />## Step 4<br />The fourth blank is about the type of maps generated using magnetic data of the ocean floor. This is referred to as "geomagnetic time scale" maps.<br /><br />## Step 5<br />The fifth blank is about the temperature of the ocean floor near ocean ridges. This is referred to as "hotter".<br /><br />## Step 6<br />The sixth blank is about the temperature of the ocean floor near deep-sea trenches. This is referred to as "colder".<br /><br />## Step 7<br />The seventh question is about a device that can detect small changes in magnetic fields. The correct answer is "crust o meter".<br /><br />## Step 8<br />The eighth question is about minerals that act like small needles and record the orientation of Earth's magnetic field at the time of their formation. The correct answer is "iron".<br /><br />## Step 9<br />The ninth question is about a type of line that connects points on a map that have the same age. The is "isochron".