16.5 1. What is the foreshore, or intertidal zone? 2. What is the difference between a spit and a baymouth bar? 3. On beaches with multiple landowners, why does the construction of one groir often lead to other groins? 4. What causes some coastlines to be rocky?

1. The foreshore, or intertidal zone, is the area of a beach or shoreline that is exposed to the air at low tide and submerged at high tide. It is the region between the high tide mark and the low tide mark.<br /><br />2. A spit is a narrow strip of sand or gravel that extends from the land into the sea, while a baymouth bar is a sandbar that completely closes off a bay. Both are formed by the deposition of sediment carried by longshore drift.<br /><br />3. On beaches with multiple landowners, the construction of one groin often leads to other groins because groins are structures built perpendicular to the shoreline to trap sand moving along the beach in longshore drift. When one groin is constructed, it disrupts the natural flow of sand, causing erosion on one side of the groin and deposition on the other. This can lead to the construction of additional groins by other landowners to prevent erosion on their property.<br /><br />4. Some coastlines are rocky due to the presence of hard rock formations such as cliffs, headlands, and bays. These features are formed by the erosion of softer sedimentary rocks by wave action, leaving behind the more resistant hard rocks.