We find the rock hewn churches where there is sandstone although the converse is not necessarily true. The Tigrai region is characterized by rock assemblages that cover a wide geological time Spain.The southern part is represented by Cenozoic volcanic rocks, the central and part of eastern Tigrai is represented by Paleozoic and Mesozoic sedimentary successions (the Edaga Arbi Glacials, the Enticho sandstone the Adigrat sandstone and younger successions of the Mekele outlier). The northern and northwestern parts which extend to Eritrea are dominantly characterized by steeply dipping and extensively folded, rather low grade metamorphic rocks.
All groups of rock hewn churches are clusted and carved from Enticho or Adigrat sandstones exposed by faulting or erosion. All the evidences indicate that the locations of the rock-hewn churches are far from arbitrary. They are rather systematic and governed by one important factor the rock type i.e. they are all carued in to the sandstone.