In this photo, looking west, you can see three distinct layers: 1. the first layer is the Cabernet vines that are roughly 20 years old; 2. the ridge of the pine-covered north-west Mayacamas mountain range, and 3. the distant coastal range, which is slightly newer than that of the Mayacamas. These ranges are likely between 20-50 million years old.
It is thought that the subduction of two different continental plates caused these mountain ranges to form, which, in essence, makes the mountains on the edge of the sea newer than those inland (at least on the west coast of the US). It appears unclear exactly when these ranges formed, but estimates are that 100 million years ago the California coastline was located about where the present-day Sierra foothills lie. It is also estimated that about 10 million years ago the Mayacamas range started to erupt, with many small but long-lived volcanos. This volcanic activity is thought to have ended around 2.5 million years ago, and is one of the reasons the local soils are so effective at producing world-class wine.
So, looking west you see a bit of a time warp: relatively new vines, and then older to newer mountains.
For me, looking at geology always provides great context and perspective into how amazing it is that so many factors had to come together to make this place able to produce wines of such quality. Humbling.