SLATE - THE DELTA STORY
A HERITAGE TO BE PRESERVED
Tribute to the Delta Area
The book "The
River and the Ridge - 300 Years of Local History" can be obtained through the Old Line Museum, P.
O. Box 35, Delta, PA 17314. Cost of the book is $35.00 plus
$2.10 tax and $5.00 for shipping the thick book.
Congratulations on the 150th anniversary of historic Delta!! The
book is well worth the money with 300 pages, plenty of photographs and
"Welsh Settlers of Delta,
PA./Cardiff, MD" by Jack Jones and published by the Historical Society
of Harford County, Inc. can be purchased for $5.00 from:
243 Equine Cove
Red Lion, PA 17356
Tele. (717) 246-7100
Jones presented a paper at the 2005 Geological Society of America's
Northeastern Section meeting in March on the history and heritage.
Below is the abstract and reference.
Northeastern Section - 40th
Annual Meeting (March 14–16, 2005)
Paper No. 14-2
Presentation Time: 8:30 AM-8:55
THE PEACH BOTTOM SLATE IN SOUTHEASTERN PENNSYLVANIA -
ONCE THE BEST BUILDING SLATE IN THE WORLD
JONES, Jeri L, Jones
Geol Svcs, 276 North Main Street, Spring Grove, PA 17362,
The Peach Bottom Slate (PBS) is found within a complex
metamorphic terrain in Lancaster and York counties, Pennsylvania,
extending into northern Harford County, Maryland. The formation is
considered to be Ordovician in age, but its structure is still not
completely understood. The earliest known quarrying of the slate
goes back to Welshman John J. Roberts in the 1730’s. The first
commercial slate quarry in the United States was opened in this
area in 1785. In 1843, a large Welsh migration brought experienced
miners into the area. With the introduction of the Welsh, a new
technique of straight-walled deep surface mining was introduced.
Approximately 34 quarries once operated within the PBS on “Slate
Ridge.” At the 1850 World Expo in London, England, the PBS was
voted the “best building slate in the world.” Uses for the
slate included grave markers, shingles, sidewalks, windowsills,
fence posts and stove plates. The slate has been used in many
federal and state buildings as well as the Biltmore Mansion in
Asheville, North Carolina. The final use of the slate in the
1930’s and early 1940’s was roofing granules at the
Funkhauser‘s Quarry. Due to it’s higher than normal content of
silica and aluminum, the PBS keeps its original color and does not
weather. A local church has had a PBS roof on it for 200 years
without any leakage.
(Click on any image below to enlarge
| Delta, a small
community in the southeastern corner of York County,
Pennsylvania, is probably thought to be more closely associated
with Baltimore, Maryland instead of York, PA. It was within this
community, in 1851, that a "backyard" mineral resource would
take this small, sleepy town into the center of stardom for
slate. At the London Expo that year, the Peach Bottom Slate was
judged to be the best decorative slate in the world. Many eyes
focused their future onto Delta, including the Welsh, which
actually started their migration to the area in the mid 1840's.
With their knowledge on deep, straight wall mining from Wales,
the Welsh educated the Scotish-Irish residents on extracting the
maximum tonnage of slate from the quarries.
High altitude view of Delta (lower center) and Peach Bottom
Atomic Power Plant and Susquehanna River along right side.
| The Peach Bottom Slate
District is certainly one of world fame. Although the discovery
of the slate in Delta is credited to Welshman John J. Roberts in
the 1730's, the first commercial slate quarry in the United
States was opened in this area in 1785 by William Docher. All of
the slate quarries were situated on the original McCandless
property and later owned by the Williamson estate. Slate Point,
located just south of the Peach
Bottom Atomic Power Plant, is believed to be the location of the
first quarrying in the area. John Cooper was the original owner
of the property, but sold it to his grandson, Steve Thomas
Cooper in the 1790's. Steve struck a deal with a John Kirk "to
allowing the quarrying of slate for 99 years, at $.01/year until
Kirk begins quarrying, $30/year for the first 7 years of
quarrying, $60/year thereafter.” Although the history of these
pits is quite scarce, it is believed that the slate was hauled
by wagon to Peach Bottom, which is now the site of the atomic
power plant. From atop Slate Point, which is owned by
Philadelphia Electric Company, a great view of the Susquehanna
River can be seen.
The role of a
slate miner was a semi-skilled occupation. Wages were low for a
ten-hour day, and the work was very hard and dangerous.
Loosening the large slabs of slate from the vertical quarry
walls while supported on a platform and removing to the sawer's
shanty was risky. Not only was skill involved in being a miner,
but also a lot of luck hoping that the machinery, tools or
cables would not fail and cause a serious accident. Loosening
the slate from the walls was not done by dynamite as originally
suspected. Dynamite was too strong and would seriously fracture
the rock. The lower-energy black powder was used to soften the
blast, after which large wedge chisels were pounded into the
fractures to slowly heave the slate block loose. The slabs
removed were twelve feet by eight feet.
With the introduction of the Welsh in the
1840's, they brought with them the art of removing the rock working on a
platform suspended by a cable and hoist. This method is what produced
the vertical walls in the quarries and not having ramps and levels as
you see in modern quarries. This was a dangerous way to work but allowed
the maximum amount of slate to be removed for a particular operation.
Cables ran across the quarry. From these ran
trolleys and with other cable rigging, the workers were able to lift the
slab out of the excavation. Splitting the slate was another talent only
mastered by a few. In 1929, 263,668 squares of slate were produced
(Ashley, 1931, A Syllabus of Pennsylvania geology and mineral resources,
PA. Geologic Survey, 4th. series, Bulleting G1).
Jones Quarry as photographed in 1999. Pit is about 800 feet
long, 100 feet wide, and 70 feet deep to the water elevation.
Water is about 70 feet deep.
waste pile at the Jones Quarry. Low quality slate and overburden
was dumped here.
| Slateville Presbyterian
Church was organized in 1849 by a few members who separated from
Slate Ridge Presbyterian Church. The cornerstone was laid on
September 7, 1849, the date of the inception of the
organization. Dedication occurred on June 8, 1850. In 1867, the
congregation saw that the building was too small and built a new
structure at a cost of nearly $7,000. This building was improved
and renovated in 1884.
Notice the scribe marks. This is a testimony to the
high quality of the slate.
The patience that Mr. Evans had in
carving the markers was outstanding
Within their cemetery, the difference
between the granite, marble and slate grave markers is quite
noticeable. One problem that helped lead to the slate’s demise
was that the slate was too durable to the weather. Engraving on
the slate dating back to the late 1700's looks "like new" today.
The life of a Peach Bottom slate roof is often 150 years. The
colonial interior of the church includes the original stained
glass windows, oak pews, and a Midner-Losch pipe organ which was
installed in 1927. Carillon bells added in 1972 contribute to
the music heard daily throughout the Delta countryside. The
church celebrated their 150th anniversary in 1999. The church
has been the "lunch stop" for the tours that Jeri Jones leads
into the area, either through Jones Geological Services or with
the York County Parks.
the slate sidewalk, steps and church tower roof.
Presbyterian Church cemetery, a great place to inspect the Welsh
language and slate engravings.
Robert E. Evans carved all of
the gravemarkers in the cemetery. Oddly, his is a plain marker.
| The Welsh families
needed to settle someplace close to the quarries. Because the
Welsh were a close-knit group, they basically did everything
together. Along with their love to quarry slate, much of their
social time was dedicated to two of their other loves: the
church and music. The Welsh constructed vernacular style
cottages in nearby settlements. The only remaining settlement of
three is Coulsontown. The cottages were replicas of the miner
villages found in the mountainous Snowdonia region of northwest
Wales. Main Street in Coulsontown is about 600 feet long and
gravel paved. Main Street today consists of a few vacant lots,
several modern homes, a two and one half story framed cottage
and four stone quarrymen's cottages. Cornerstones are large,
well-shaped quoins. Door and lintel blocks are one single block.
The walls are composed of the Cardiff Conglomerate, that’s found
locally. Roofs are covered with slate. A distinctive feature is
the four courses of cornice made of brick. Brick was considered
a luxury item in Wales, thus the bricks here represent a symbol
of their new economic status in America. The Old Line Museum has
purchased two of the cottages and are currently are going
through extensive renovation back to the 1850’s look.
A cottage constructed with the Cardiff
Conglomerate. Walls are about two feet thick. Notice the double
| The largest quarry in
the district is that of the the Funkhouser's Quarry. Once three
separate operations, the quarries were combined, for a total
length of about 1200 feet with vertical walls and water-filled.
This was the site of the last slate operation in the area,
shutting down in about 1944. The mining was extended northward
by tunneling. The worst accident in the quarrying history of
Delta occurred here in the early 1900's, when seven men were
killed in a tunnel by a dynamite blast. The last products
produced here were that of roof granules, although high-grade
roof shingles were also produced. The product was hauled to the
mill by railroad. Remnants of the mill can still be seen on the
north side of Atom Road. Because of its easy access into the
bottom of the quarry, this location has been a popular swimming
area. Although the property is heavily posted with signs,
Funkhouser's Quarry has been proclaimed by the U.S. Department
of Labor, Mining Safety Division, as the second most-deadly
quarry for drownings in the country.
of the Funkhauser quarry looking southwest
Company of Hagerstown, Maryland operated the last slate business in this
talk about the Delta area without including the Cardiff Marble
Company, just south of Delta in Cardiff, Maryland. The site was
famous for its own mineral resource, "Green Marble" or what
geologists term a serpentinite. The greenish rock is a
metamorphic rock consisting wholly of serpentine minerals
commonly derived from the alteration of peridotite. In turn,
peridotite is a coarse-grained igneous rock formed very deep
inside the earth. The operation was originally a quarry being
used for road construction, but in 1913, a blast exposed a piece
of the serpentinite. The quarry sent the rock to Baltimore for
polishing, after which it was determined that a new resource has
been discovered. After changing their equipment to concentrate
on the beautiful rock, rapid expansion of the quarry started. At
the completion of the operation in the early 1970's, the shaft
extended to a depth of over 300 feet with numerous tunnels at
various levels. Huge blocks of the serpentinite were lifted out
by horst and cable, similar to the slate operations, and removed
to the saws in nearby buildings. The rock was used for
decorative stone, lamp bases, table tops, fireplaces, and desk
ornaments. The rock was used as decorative stone in the Empire
State Building in New York City, the Department of Highways
Building in Harrisburg, along with the bottom of the walls in
City Hall in York, PA and in numerous federal buildings in
and cable device to raise large slabs of the serpentinite out of the shaft
as seen in 1999.
Cart used to transport the rock
through the saw.
shaft as it appeared in 1999.
| So, what has happened to the heritage of the Peach Bottom slate
industry and the Cardiff Marble? Due to the efforts of many of the
residents who grew up in the community, the heritage is stronger
As I found out when organizing my first fieldtrips
there and continue to see, area residents love to talk about the
heritage. The Old
Line Museum in downtown Delta is a great way to discover the
heritage. Filled with artifacts, photographs and clothing, a
visitor can quickly find themself living in the 19th century.
The museum is also home of the world-famous "Slate Clock", a
one-of-a-kind creation, made by Humprey O. Pritchard, a life-long slate
miner. The clock stands seven feet and two inches tall, thirty
inches wide and over one foot deep. Three different slates were
used in the production of the clock: Peach Bottom deep blue slate,
Bangor, PA silvery gray slate and red slate from Vermont. The
museum is open Sunday afternoons, May through September from 1:00 - 5:00
pm and by
appointment. Email them at firstname.lastname@example.org.
World famous slate clock
| The geology of the
Delta area is still one of those mystery areas. The first
research conducted by George Stose and Anna Jonas in 1939 mapped
the area as being a syncline, with Peach Bottom Slate in the
middle, and the Cardiff Conglomerate and the Peters Creek
Formation scists laid on the limbs of the fold. Since the
Cardiff Conglomerate is absent on the northern limb, Stose and
Jonas placed a fault along the north side, between the slate and
the Peters Creek Formation. Other researchers who mapped in the
area saw evidence for an anticline and not a syncline (Michael
Higgins from the U.S. Geological Survey, among others). The most
recent research was conducted by David Valentino, who at the
time was employed by the Pennsylvania Geologic Survey, and he
could not determine what type of folding was involved and
proposed the name "Peach Bottom Structure" to the fold instead
of the "Peach Bottom Syncline”. With the complex geology and
limited outcrops of bedrock (obviously most of the slate is
exposed in vertical-walled quarries where one cannot look
closely at the structure), the formation of this area is still
debated by geologists.
Because of the lack of fossils and the amount of
folding in all of the formations within the Uplands Section of
the Piedmont, the Peach Bottom Formation has been assigned an
Early Paleozoic Era date.
of Stose and Jonas (1939) showing the Peach Bottom Formation
| Finally, it was
discovered in the late 1970's by amateur mineral collector,
Donald Schmerling, that gold occurred in several of the streams
in the area. Today, about 15% of streams in York County contain
gold. Although gold has not been found in place with bedrock,
panning within several of the slate quarries did produce gold.
Several other good localities include the Delta Fish and Game
Club along Peaks Peak Road, along the same streams further north
where they intersect with Muddy Run near Castle Fin, and in
Robinson Run, north of Delta. To the west of Delta, at
Constitution, several small streams have produced gold and nice
crystals of rutile. The largest gold found in this area is about
0.75 inch, apparently associated with the Peters Creek Formation
lines in left center (above "BO" in Bottom) and along the
right top side of map represent streams that contain gold north of
|Large Mills Quarry; K - Lloyd Quarry; L -
Stewart Quarry; M - Electric Quarry; N - Edwards Evans Quarry; O
- John Williams Quarry; P - John Humphrey Quarry; Q -
McLaughlin Quarry; R - A small un-named opening; S - Faulk
Jones Quarry; U - Johnson Quarry; V - R. L. Jones Quarry.
Bold represents quarries that were combined to produce the
Funkhauser Quarry. The belt extended into Maryland for a
distance of 1.5 miles and into Lancaster County for about 5
miles. The entire slate area is only about 0.25 mile wide. The
dark line crossing the map from the lower left to the upper
right represents the proposed fault between the Peach Bottom
Formation and the Peters Creek Formation. Hashed boundary on
south side of slate represents the approximate contact of the
Peach Bottom Slate and Cardiff Conglomerate.
| The Rehobath Welsh
Church is one of only three such congregations in the United
States. Weekly services are still held here in the native
language. Two Welsh Hymn Sings are held in May and October
The Rebobath Welsh Church
The original Delta Jail is built out of the Peach
Bottom Slate. The walls are 18-inches thick. Many of the slate
blocks saw the saw marks. Even this building is well maintained
to preserve the heritage of Delta. No, the author didn’t do
anything wrong to be behind bars, just the creative idea of his
Delta Jail made of slate