noun (plural strata /ˈstrātə, ˈstra-/)
late 16th century (in the sense 'layer or coat of a substance'): modern Latin, from Latin, literally 'something spread or laid down', neuter past participle of sternere 'strew'
In Latin, the word stratum is singular and its plural form is strata. In English, this distinction is maintained. It is therefore incorrect to use strata as a singular: a new stratum was uncovered (not a new strata was uncovered). It is also wrong to create the form stratums or stratas as the plural: a series of overlying strata (not overlying stratums or overlying stratas).