Purpose: This EarthCache is published by the Connecticut Geological and Natural History Survey of the Department of Environmental Protection. It is one in a series of EarthCache sites designed to promote an understanding of the geological and biological wealth of the State of Connecticut.
Supplies: You will need a copy of this login to answer the questions once on site and be able to take a few photos on site. Spoilers may be included in the descriptions or links.
Location: N42 00.650 W 073° 17.530
Directions: The furnace is located on Lower Road, East Canaan, CT. To reach the furnace, take Route 44 to East Canaan, CT. Note the Canaan Congregational Church on the south side of the road. Turn onto Lower Road.
History of the Park: The Beckley Blast Furnace was one of three blast furnaces in operation along Lower Road and the Blackberry River in East Canaan during the period 1832-1923. It was built in 1847 by John Adam Beckley, great-grandson of Esquire Samuel Forbes and grandson of John Adam, Jr., founders of the Forbes & Adam Iron Company. The Beckley Furnace (East Canaan #2) produced pig iron until the winter of 1918-19. Constructed of locally quarried marble, the furnace was originally thirty-two feet in height and thirty feet square at the base. Later the height was raised to forty feet making it one of the largest of forty-three blast furnaces in the Salisbury Iron District.
Beckley Furnace closed in the winter of 1919 at the conclusion of World War I. After it’s closing the buildings and stack slowly deteriorated. Then, in 1946, Civil Engineer Charles Rufus Harte developed a plan for state purchase and preservation of Beckley. In the process the Beckley Furnace was designated as Connecticut's sole official state Industrial Monument and in 1978 Beckley was placed on the National Register of Historic Places.
The Process of Making Iron : Today it is very difficult to find evidence of the industrial past of the Upper Housationic Valley. More than 40 blast furnaces and foundries took advantage of the co-location here of the key natural resources needed to make iron (high grade iron ore, limestone, forests to provide charcoal, and water power) and then to fabricate products such as railroad wheels with the locally produced iron.
Iron ore occurs in only five forms in Connecticut: as magnetite deposits in rock, magnetite in beach placer deposits, as limonite deposits in rock, limonite in bog iron, and as a carbonate deposit. All are easy to purify
(smelt) simply by heating in a furnace with charcoal. Chemically, it is a reduction reaction. Carbon from the charcoal combines chemically with oxygen in the iron ore-mineral releasing pure molten iron that collects at the bottom of the furnace.
Bog ore. Iron is soluble when in a chemically reduced form but is very insoluble when it is in an oxidized form. Iron was dissolved from regional bedrock by reducing ground waters. When the iron-bearing groundwater came to the surface as springs that fed local bogs, the water oxidized resulting in the precipitation of iron as the mineral limonite in the bog sediments. Bog iron ore, in the form of rusty brown lumps of low density, occurs in or near the surface of swamps fed by springs carrying iron in solution. As such it is a relatively recent deposit, having formed since the last Ice Age (~17000 years ago). Mining bog iron ore was relatively simple: scrape it up, wash off the mud, let dry then feed directly into a furnace or forge.
Limonite ore (rock). Limonite deposited in the local bedrock is denser and typically darker in color. In the Salisbury District it is mixed with goethite, FeO(OH). Mineralization occurred to rocks of the Walloomsac Schist (Ordovician in age) near its contact with the underlying the Stockbridge Marble (Cambrian in age). Mineralization probably occurred during the last period of metamorphism in late Devonian time. Mineralizing fluids dissolved iron from the schist and were then transported until they were oxidized at or near the contact with the marble. Mining the limonite rock ore was also simple: most of it was taken from open pits where it was dug, sometimes with the aid of blasting. The ore was hauled by horse-drawn carts to where it was processed.
Smelting. Processing of the ore consisted of crushing, removal of non-ore contaminants, and mixing with marble. This mixture formed the charge that was loaded into or near the top of the blast furnace with equal charges of charcoal. The temperature achieved by burning the charcoal was a function of the rate at which the oxidation reaction occurred. Experience showed that maximum temperatures could be achieved with a continuous supply of air blasted into the furnace through ports near its base. In some cases the air was pre-heated before being blown into the furnace. At the same time the air was being pre-heated, water could be converted into steam and used to power the air-blast machinery. The blast furnace was essentially a large chimney with a slightly wider portion about two-thirds of the way down. The wide portion acted like a firebox. It narrowed toward the base where the air-ports were located.
The charge, loaded into the fiery furnace, slowly worked its way toward the bottom. Along the way the carbon in the charcoal combined with the oxygen in the iron ore and escaped out the top of the stack (chimney) as carbon dioxide and carbon monoxide. The iron was left behind in a molten state and it collected at the base in what was referred to as the “crucible”. Impurities in the iron combined with calcium from the marble and formed a lighter material referred to slag, which floated on top of the iron in the crucible. Periodically the crucible was tapped allowing the molten iron to flow out into channels dug into wet sand outside the furnace. They were placed there to collect the molten iron and allow it a place to cool and solidify.
The 10-ton chunk of iron on display at this site formed in the hearth area of the furnace. While there are a number of things that can cause its formation this one was probably due to a failure in the masonry of the hearth, which allowed the molten iron to break through the side of the crucible. These chunks can also form on the side of the furnace stack if the ore and limestone were not properly loaded, clogging one or more of the tuyeres or air ports, putting the fire out by preventing air from getting into the furnace.
- What are these large single pieces of iron called and how many of them have been discovered at this site?
Drawing on the high quality ore from nearby Salisbury, marble from local quarries and charcoal made from the surrounding hardwood forests, the forges and furnaces of East Canaan played a major role in the development of the nation’s iron industry.
The large crown gear resting near the upper section of the stonewall drove the blowing engine to produce the required airflow. Since Beckley was a hot blast furnace, the air passed through a preheating over before being sent to the furnace stack itself. The size and shape of the enclosure where the turbine is now suggest that it originally held a water wheel. The turbine must have been considered the latest in technology when it replaced the water wheel. While waterpower was cheap and clean it was not a reliable source of power.
- From the Turbine interpretive sign name two of three reasons water caused the furnace to be shut down.
If you look over at the Blackberry River you will notice that part of the river-bed flows over bedrock (ledge) and part of it flows over sand and gravel that we refer to as alluvium. The rock is composed of impure dolomitic marble that is relatively easy to erode. Close to the shore of the river several curious holes are found in the rock. These are referred to as potholes. They are formed by abrasion of the rock localized by swirling eddies in the stream bottom. Rock fragments and sand grains are swirled by the water power and
rub and smash against the rock, gradually drilling a hole in the ledge. There are a number of small potholes at this site that are mostly about 6” in diameter and up to a foot in depth. A few are larger and a few are smaller. Potholes are known from other sites that are a foot or more in diameter and 10’s of feet in depth. These are just small puppies. Take a picture showing at least two potholes from this location.
To log this EarthCache: Answer the questions, and send a photo at the site and number in group.
Historical Information provided by the Friends of the Beckley Furnace, Inc.
Additional photos and information available at: http://www.betweenthelakes.com/
2-1bBq iron furnace slag heap P P P Yes Beckley Sate Historic Site Northwestern Connecticut’s iron hills heritage an analysis of restoration by: Jonathan Clapp
Images of America Connecticut Mining by John A. Pawloski, (2006) Arcadia Publishing