subject：Big Erecting Rocks scenic spots：Swallow Grotto author：Lin Cheng-yuan date：2006/10/4 info： Between spring and summer, swallows can be seen darting between the cliffs on both sides of the river, and their chirping can be heard too. The marble cliffs have been washed and cut by the water for thousands of years, forming peculiar wrinkles and amazing features. At the bottom, the features resembling the side profile of an lndian chief form a most amazing masterpiece of Nature.