This was a popular sightseeing spot for Oregon and California Trail emigrants in the mid-1800s. It is just one mile (1.6 km) from the trails and users were not yet exhausted...or sick of rocks!

The girl is throwing pebbles into the water. She has just launched one, a white egg shape head-high between V-shaped main limbs of the shoreline tree. The image shows motion blur at 1/500 of a second. A companion image shows her excellent follow-through.