The lower unit of the Member 2 of the Mila Formation in Tuyeh - Darvar area (48 km southwest of Damghan) consists mainly of carbonate rocks. The unit is overlain by the upper unit of the Member 2 and is underlain by the Member 1 of the Mila Formation with unconformable contacts. Storm deposits of tidal flat to distal open marine have been recognized. The cast of late Middle Cambrian Ptychoparioid trilobite has been recognized in the distal open marine storm deposit. These rocks have been deposited in a storm - dominated ramp on the western part of northern passive margin of Gondwana