Complex sentence: Deposition took place throughout most of the Jurassic period, from the Hettangian stage to the mid-Tithonian, as determined from its fossil content, including ammonites, molluscs and microfossils.
Split into simpler sentences: Deposition took place throughout most of the Jurassic period, from the Hettangian stage to the mid-Tithonian. The age is based on its fossil content, including ammonites, molluscs and microfossils.