Strata is a term we use in geology and stratigraphy, which is the rock layers/bands clearly defined like in the photo above. The word stratum is for one layer, whereas strata is for multiple layers. The photo above is by calwest on Flickr, which is a photograph of the Badlands in South Dakota.

Strata is a term we use in geology and stratigraphy, which is the rock layers/bands clearly defined like in the photo above. The word stratum is for one layer, whereas strata is for multiple layers. The photo above is by calwest on Flickr, which is a photograph of the Badlands in South Dakota.