a person can get enamored by looking at these rocks through the water.

The color of the rocks is determined by the presence or absence of iron. The bright red rocks found along the Grinnel Glacier trail were deposited in a shallow ocean environment where the iron was oxidized by the tidal exposure to the air. Rocks with this coloration often have old ripple marks or ancient mud crack lines.

The rich green-colored rocks were formed in deeper water than the red rocks. Although these rocks contain the same quantities of iron-bearing minerals, they did not have the same exposure to oxygen and the amount of oxidization was limited.

These rocks are actually all around Glacier National Park, and were formed at different eras. When the glaciers came, it broke down the rocks into tiny fragments and the rivers washed them away. Many of these got deposited onto the lakes and "tarns" —lakes formed by filling the bottoms of ice-scoured amphitheaters. Water erosion then rendered them into smooth pebbles.