PRIDEAUX PLACE, PADSTOW
THE GROUNDS, GEOLOGY and SOIL
in the construction of
Padstow sits on the edge of the Camel Estuary, being on the "back" of Gunver Head. a rise of upper Devonian rock, having areas of greenstone/dolerite, the nearest granite is to be found on Bodmin Moor. The Original Grange Manor house appears to have been built of a different slate from that used for the remainder of the house (1588-1592), but inspection of samples taken, merely show that they were removed from different parts of the same quarry. It seems that the quarry was first worked when the Priory Tithe Barns and local cottages were being built.
The base soil is clay and silt, generally acid and damp. The ground is a rich mass of leaf compost, offering perfect conditions for plant propagation and growth.
The house is built of slate taken from the same quarry on the opposite side of the road from Place, a very distinctive stone, which has proved almost impossible to match, due to the peculiar range of discolouration in aging, which takes place. The greatest difficulty arises when masonry is removed and the stone expands when loads are removed, it is therefore impossible to repair the wall as it existed. Any stone removed MUST be stored under load pressure.
Granite was used to form opening frames for doors and windows, this granite appears to be a moor stone, Metamorphic, showing signs of China Clay.
Upper Devonian rock includes Purple, Green, Delabole Slate for this stretch of Cornwall. Ostracod slate occurs in the Padstow area, with the banded slates ( purple and green ) lying in the St. Minver synclinorium and are at least 400 feet thick. This is mentioned here in that these were used to form the top of the Dairy rear wall, grotesque work, assumed to be in 1770, when the long Green Walk was extended to it's present form from being an access to the Bowling Green. The purple variety is also used in featured garden walling around the grounds.
Besides the general Slate, there are "grotesque" works, of crystal based granites and other "imported" stone, presumably selected at the assistance of Dr.Borlase, by Humphrey Prideaux, around 1770. The entrance steps of the Library are flanked with "pool" rocks, which are the same slate from the local quarry, which have been shaped by the flow of water, where the water used to flow in a stream from the rock face, prior to the quarry being depleted.
The other stone in use at Prideaux, is Cataclews ( Carrack Loos, as it used to be ), a blue-grey Greenstone from a proterobase sill near Trevose Head : similar to this is the more durable Polyphant picrite or the Duporth picrite. Some of the features, used in the building or found in the grounds, are probably retrieved from the demolished Chapel of St.Samson ( see notes elsewhere ).
The granite, as before 1800, was largely removed from surface blocks or debris, generally known as Moor Stone. It seems likely that the granite used for Prideaux Place came from the St. Austell region, perhaps Roche being broken clitters, worked and dressed where they lay. In any event it is sure that the Grange Manor was built of local Slate, the remainder of the house being built of the same Slate with later alterations and additions using a mixture of the remnants of the quarry and the tunnel excavation, together with Slate from St. Minver and Trevose Head being a black Slate. Features of the external walling of the Grounds are built of the Metamorphic Granites of Savath/Helman Tor region.
A final note, of particular importance, is that The Temple, Seat and Obelisk ( refer to notes elsewhere ) are made of "Bath Stone", the first use of this stone in Cornwall. When the Obelisk was demolished to form the access drive at the South Entrance, parts of it were used to form the base feature strip, matching the granite strip of the East Entrance off the front terrace.