system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why do asphalts fade after time?

When asphalt is first laid, they are black~charcoal. However, after some time, the color fades and the asphalt becomes gray.
AFAIK, asphalt is the densest, thickest byproduct of petroleum and it's not like its only dark on the surface. Shouldn't the color be consistent even after some time as it's the same thing inside and out?
gpt
What I’m not seeing in the comments is a lot of asphalt roads aren’t just petroleum product. The petroleum product is the binder and the road is mostly composed of aggregate (stones). If the outer layer of tar wears down you’ll see the rock.