|
History of bluestone
The majority of Bluestone Association
members are removing stone from parts of the Catskill foothill
region of south central New York State. The hills typically are
gently rolling with vertical relief of up to 1000 feet. The
bedrock of these hills is comprised of sedimentary sandstones,
wackestones, siltstones and shales. The compositional and
depositional history of these stones lithologies are unique to the
area south-central New York and north-eastern Pennsylvania.
The uniqueness of the stone has earned its name
"Bluestone", which can be found nowhere else in the
world but the Catskill region foothill region.
The sandstones/wackestones, which
make up the bulk of commercial "Bluestone", were
deposited during the Devonian period of the Paleozoic Era.
The Devonian Period lasted from approximately 345-390 million
years ago. At that time a vast salty, shallow inland sea
spread to the west. To the east a large mountain range
(equal or larger that present day Himalayas), rose to provide a
ready source of clastic material. This material was brought
to the region by numerous small and large rivers and tributaries,
which comprised what is now called Catskill Delta Complex (think
of much larger Mississippi River Delta). This Delta Complex
drained to and met inland sea in the area surrounding Deposit,
Masonville, Hancock and points west varying times.
Near shore to non-marine sand bars,
filled stream channels and mudflats making up the present day
rocks of the area. If you look closely at these lines, which
represent episodes of deposition, of sand or silt with layers of
organic mud in between. These lines, which represent episodes of
deposition, such as cross bedding, ripple marks and cut and fill
features. Fossils and brachiopods (type of clam) and other
marine fauna, or pieces of trees and vegetation can be found
through the region. Sorry, no dinosaur fossils, 120 million
years too early.
Today all sandstones from the area
are called "Bluestone" even though they may be any color
from tan-brown, lilac, red, blue to even green. The color is
determined by the mineral assemblages of the particular stone and
the cement that holds it together. The true-blue Bluestones
are typically feldspathic/quartz sandstone with silica cement.
This is a highly durable and beautiful stone. Accessory
minerals in the stone include micas, iron (magnetite, hematite)
and clay cements. Tiny flashes of silver iridescent color in
the stone are flakes of mica. Mica and iron tend to make the
stone tan or brown in color. most red stains on the rock are
the result of iron leaching from the rock and staining it.
|
DIMENSIONAL TOLERANCES
A) PAVING THICKNESS
5/8" Nominal
+1/4" & 1/8"
1" Nominal
+/-1/4"
1 1/2" Nominal
+3/4" & 1/4"
2" Nominal
=/-1/2"
2" Minimum
Thickness Tolerance varies dependent
on quarry conditions
B) FACE DIMENSIONS
Quarry Cut -Length/Width/Squareness
+/-1/4"
Shop Cut -Length/Width/Squareness
+/-1/8"
C) EXPOSED EDGE DIMENSIONS
Quarry Cut Height +/-1/4"
Shop Cut
Height +/- 1/8"
D) FLATNESS TOLERANCE
Surface variation not to exceed
=/-1/8" each sq.ft. of exposed edge
E) BED JOINTS
Allow 1 1/2" bed for setting
Allow 3/4" bed setting for
treads, coping and sills
F) BACKS OF STONES
Backs of all pieces may be natural or
sawn
Backs of paving may not vary more
than 1/2" in 12"
Backs of treads, coping & sills
may not be more than 1/2" in the bed
|
