As the island has risen and the seawater has retrieved gradually, the surface area of the island has increased. The Tandis Valley is part of those areas which have been once underneath the water, and when pulled up, it has been heavily eroded by sea waves among other factors. This type of erosion gets reduced gradually while moving more towards the Roof of Qeshm, which has remained intact. In the Tandis Valley, similarly to other geosites, whenever the upper and harder structures (mainly limestone) that usually protect the softer layers beneath, have been degraded, erosion has been a determining factor in forming the geomorphology. However, if these harder structures remain, softer ones are also protected. This is the main reason high plateaus are observed among lower and heavily eroded lands in Qeshm Island.
At this geosite, interesting forms may be observed as if nature has been powerfully carving them through ages.

In some areas of the Valley numerous fossils may be found including fossils of bivalves, in some areas as colonies. Another interesting geological phenomena in the Tandis Valley is sedimentation forming muddy mud cracks, which has created beautiful and interesting landscapes. During and after the rainfall, it is important to pay attention to muddy areas where sometimes the mud is very sticky and dangerous to walk on at this geosite.