The formation of the cave itself probably occurred between 1.5 to 5 million years ago.

Perhaps fifteen steps lower, another such formation occurred to the left.

The formation of internet marketplaces often occurs quickly in response to social or economic trends.

Formation can also occur when waves are diffracted around a barrier.

The most intensive formation of towns occurred in 1938-1940.

During the warm-up process the formation of the active reagent occurs.

Formation occurs during embryogenesis, typically between days 33 and 41 of gestation.

The formation of Triple bottom occurs during the period of accumulation.

This particular formation occurs often in Great Britain and China.

The formation of this mineralisation occurred in several stages.