Oceanic deposits, like the Upper Chalk, are succeeded by beds of littoral and estuarine characters.
None of the rivers, except in the estuarine parts, is navigable.
Thus in these lowland or estuarine peat-mosses the moss eventually occupies the water, and goes on growing.
Limestone and marine beds in the south are replaced by sandy and estuarine beds in the north.
It is an estuarine deposit like that mentioned above as occurring in the Wash off Heacham, for instance.
Slowly this sea shallowed, giving rise to the alternating estuarine marine and freshwater deposits of the Coal Measures.
The chief interest in estuarine conditions is the mingling of sea and fresh water.
We might therefore expect to find coal wherever strata of estuarine origin are developed in great mass.
A soft jet is obtained from the estuarine series of the Lower Oolites of Yorkshire.
Whether these are marine, lacustrine, or estuarine deposits, there is hardly sufficient evidence to show.