If anything, long and continuous outcrops often suggest that geology is much more varied in a vertical than in a horizontal direction. This beautiful photo from the Bisti Badlands in New Mexico, USA, nicely illustrates that. The boundary between the greyish-greenish fine-grained sediments at the bottom of the section and the overlying coarser-grained and lighter sandstones can be traced across the entire area captured by the photographer.
However, that does not mean the sandstone “hoodoos” capping the succession were once part of the very same continuous sandstone. Before that conclusion can be drawn, more information would need to be acquired through some detailed fieldwork; are these distributary channels, shoreface sands, or splay deposits? All of these options are possible within the overall shallow marine to coastal framework of these Upper Cretaceous rocks. Depending on what they represent, the sandstones may well be more isolated than one initially would think based on a first glance. That’s why a more detailed inspection of outcrops – especially the sandstones – is always required before concluding it is all layer-cake geology.
