Found this cool rock at lake Tahoe. It has 2 white rings around it that are so perfect I thought at first they were drawn. Now it lives in my Chia pet garden. Here’s an additional pic.

Found this cool rock at lake Tahoe. It has 2 white rings around it that are so perfect I thought at first they were drawn. Now it lives in my Chia pet garden. Here’s an additional pic.

I did find this on the shore but it was lake Tahoe at around 7,000ft elevation. Could it still be from the ocean in that case? You guys seem to know what you’re talking about and it’s terribly interesting. I always just thought, “cool rock” but I love hearing all these theories.
Cool rocks are legit where a lot of geologists get their start.
Could be from one of the streams leading into the lake. Could be many, many years of the small but present waves of the lake hitting the shore. Or could have been created when the Sierra Nevada were closer to sea level.
Nice. Tahoe gets huge waves from time to time. Most of my cool rocks come from that area.
Waves were my top theory.