Snake description…ID?

While walking in Big Creek Park I saw a neat snake which my husband and I have been unable to identify. It was a slender snake but when I 1st saw it from a short distance it appeared to have a zig zag body (like rick rack used for sewing projects), but as I got closer I saw that this was an optical illusion and actually the snack had alternating black then dark brown horizontal bands about 1/2 inch or slightly more its entire length. Any thoughts on what type snake we saw? It was about 18 inches long. Unfortunately I did not have my phone with me to snap a photo that day! Thank you.

It can be hard to identify snakes from a description, but it sounds like you saw a Black (Gray) Rat Snake. As juveniles, they are blotched and will appear to have alternating light and dark markings. They are also common at Big Creek Park and will sit across trails. As they age, their pattern obscures until they are nearly a uniform black color.

-Naturalist Andy Avram