this also view from inside (side view)

Mohsen, I think it corresponds to the geological formation known as karst , which geological origin is by transformation of underground deposits of gypsum. We have a similar phenomena in South Mendoza Province, Argentina. Two giant open-sky holes in the Salado river valey. Both of them correspond to the karst phenomenon called in Spanish "dolina" caused by the transformation of underground gypsum deposits that, due to the of the filtrations and groundwater produce a dissolution of the mineral and enormous caverns are formed below the surface, the land slowly sinks, causing a constant growth of the characteristic cones. The biggest one has 180 m of diameter, 80 m depth from surface to the water level, and a 20 m the deepest water depth. Let me share two pictures from websites.

Best wishes, Mario

Mario

this is travertine cones formed by hot springs , and springs still there in area. the rocks is travertine (carbonates)

regards

Mohsen, thank you. I know that, my comparison are related with the mechanism of gravitational collapse, I think is similar. Cheers, Mario

mario

thanks for your answers . yes even mechanisms not a same

Dear Mohsen, I think these cones form by solution limestone in rich-Co2 cold groundwater and then re deposition travertine when it reach surface and it get warmer. We have a similar phenomena in Takht soleyman, Zanjan Province, Iran.