Sandstone forms over the course of centuries, as deposits of sand accumulate in rivers, lakes or on the ocean floor, and the sand blends with calcite or quarts and then undergoes compression. After enough time goes by, the pressure pushes all of these elements together to create sandstone. Because not all sand is identical but instead comes in a variety of colors and grain textures, each formation has a unique appearance.
One of the oldest cities in the world is Petra, an outpost in the desert of Jordan that is more than 2000 years of age. A lot of the structures there were carved out of sandstone in the area. Instead of containing a uniform appearance, though, the weavings of color make the buildings look like they are made of marble cake or marble rye bread.
Some archaeologists have studied the formation of sandstone to determine how different layers of color ended up in the same sandstone. The most common theory is that a mixture of various sand types split into layers as the sand accumulated centuries or even millions of years ago. A similar process takes place in avalanches as the chaos of movement ensures that no two layers contain the same type of material.