1. Chapter 21 Section 3 Review Page 534

2. 1. Describe how the moon causes tides.
As the moon revolves around Earth it’s gravity pulls on Earth’s waters. This creates two high tide bulges on opposite sides of Earth and two low tides in between.

3. Moon Creates Tides

4. 2. Explain how the sun can influence the moon’s effect on tides.
The sun can pull in the same direction as the moon’s gravity and increase the size of tides. It can pull at right angles to decrease the size of tides.

5. 3. Compare spring tides and neap tides.
Spring tides happen when the sun and moon pull together to increase tide size. Neap tides happen when sun and moon pull at right angle to each other and lower the tide size.

6. Moon and Sun Create Tides

7. Spring Tides and Neap Tides

8. 4. Describe how ocean basins affect tidal patterns.
Differences in the size, shape, depth, and location of the landmasses around an ocean affect the number and size of the tides.

9. Arrival Times of Tides

10. 5. Compare the movement of ocean water in the open ocean with the movement of ocean water in narrow bays.
Tidal currents in open oceans are much smaller than those at the coasts. In narrow bays, tidal oscillations increase the effects of tidal bulges, producing larger tidal ranges.

11. Ocean Tide in a Narrow Bay

12. 6. Describe how a tidal bore forms.
Where a river enters an ocean through a long, narrow bay a surge of tidal water may flow upstream in a wave called a tidal bore.

13. Tidal Bore

14. The End