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sea-shore, and in the two estuaries were derived from this clay. 
Characteristic shells found in the clay are Turritella tereba and 
A start e borealis. Foraminfera are also marine shells which are found 
in abundance. Overlying the Boulder Clay there are submerged 
forests, peat-beds, and esturine silt. The best known and most 
interesting of the Peat and Forest-beds is that at Leasowe, which 
contains trunks of trees, including the oak, pine, ash, elder, yew, 
and birch. Many of these trees are believed by some to be in situ. 
The Peat and Forest-beds are exposed in several localities, includ- 
ing the estuaries of the Mersey and Dee, the mouth of the River 
Alt at Hightown. and at Seaforth. In making excavations for the 
Liverpool docks, beds of this description have been exposed. These 
forest-beds are indicative of a luxuriant growth of vegetation in 
comparatively recent times. The existence of these beds on the 
sea-shore, often below high water mark, according to some 
geologists proves the gradual but sure subsidence of the land in 
this district ; according to others it indicates oscillations in the level 
of the sea. • Through this subsidence, as well as by the encroach- 
ments of the sea by continual erosion, much land has been lost in 
this district, especially in the northern part of Wirral, in the Post- 
Glacial deposits. Recent deposits include Tidal silt, or Esturine silt, 
which covers large areas in the upper reaches of the estuaries of the 
Dee and Mersey, and has been formed from the deposition of 
matter by the esturine waters, and its accumulation in the estuary 
of the Dee has afforded feeding accommodation for thousands of 
sheep, which eat the grass that grows on the silt, although this 
grass is always covered by sea-water at spring-tides. 
Certain beds of clay and peat are also included in recent 
deposits. Enormous accumulations of blown sand fringe the coast 
in the district between Liverpool and Southport. About Formby 
the large area covered is particularly noticeable. In the peninsula 
of Wirral, between New Brighton and West Kirby, these sandhills 
are well seen. This blown sand consists of particles of sea shells 
blown inland from the sea-shore, and there are also fine particles of 
silicious and other sands. At Formby and Hightown, about 150 
years ago, there was a continual encroachment of these sandhills 
upon the land, and the Formby of that period was completely 
overwhelmed by blown sand from the sea-shore. This encroach- 
ment was almost entirely stopped by the extensive planting of starr 
grass, Ammophila anmdiuacca, which proved an effective remedy, 
assisted by careful embanking. 
