•
Wave-cut platform – this is a flattened area of rock that has become eroded by tide and waves, usually existing between high and low tidal areas.
•
Weathering – this is rock breakdown for any reason, such as mechanical, biological, and chemical forces.
Wow, that's a bunch of terms! Don't worry if you haven't gotten them all because you will gradually have a deeper appreciation for what they mean.
ROCK TYPES AND WHAT THEY MEAN While every rock is unique and different, this doesn't mean that you can't categorize them in some way. There are actually only three major types of rocks. These are igneous, sedimentary, and metamorphic rocks. The term igneous refers to "fire" or molten lava. Rocks of this type of form only when hot lava cools into rock. Particles can settle as this happens or minerals can precipitate to create something more interesting than a black rock. Look for different mineral grain sizes and textures. The texture depends on how slowly or quickly the lava cools. Larger crystals come from slower-cooling lava and vice versa. Some interesting options among these: •
Granite pegmatite – this is igneous rock formed near the top of a magma chamber. It has many possible colors, including quartz gray, white, pink, and dark-colored mica.
•
Diabase – this is rock solidifying just below the earth's surface. It cools rapidly, giving rise to a salt and pepper appearance. Basalt and gabbro are identical but differ in the size of the crystals. Diabase is in-between the two. Gabbro has the largest inclusions. Figure 1 shows a boulder with some diabase and gabbro in it:
12
