National Historic Site
Hopewell Furnace is one of the finest examples of a rural American 19th century iron plantation. The buildings include a blast furnace, the ironmaster's mansion, and auxiliary strutures. Hopewell Furnace was founded in 1771 by Mark Bird, the first ironmaster.
The iron industry was already well established in the colonies by the time of the Revolution, with a total production exceeding that of England. Beginning with the Iron Act of 1750, the mother country had attempted to curtail the manufacture of finished iron products by the colonists. Mercantile trade policy called for the provinces to supply England with raw materials which would then be turned into manufactured articles and resold to colonial buyers. But the expanding appetite of the colonies for iron products created a lucrative and immediate market that American ironmasters could not ignore. The money in ironmaking lay in selling the illegally finished products rather than in shipping raw pig iron to England. Despite the British regulations, which were poorly enforced, Mark Bird began casting stove plates soon after his new furnace was built in 1771. And when the Revolutionary War began, Hopewell helped meet patriot needs for armaments and ammunition.
Molded or cast iron articles were the end products of a relatively simple process – one that was first developed in the ancient world. The raw materials needed – iron ore, limestone, and hardwood forests for charcoal – were all readily available in the Hopewell area. Miners dug the ore from nearby open pit mines and washed it in the stream. Teamsters hauled it to the furnace.
Charcoal making was a more exacting, and dirtier, operation. Woodcutters chopped 25 to 50 cords of hardwood billets for each circular “hearth” in the woods. The heart was simply a round, level area 30 to 40 feet in diameter, cleared of debris, roots, and stumps. There from April to November, skilled colliers stacked the billets at an angle against a central wooden chimney. The covered the rounded cone-shaped structure with thin “lapwood,” or sticks, over which they spread layers of leaves and dust to keep out excess air. Finally, they filled the chimney from the top with chips of dry kindling, and then ignited it. After covering the top, colliers constantly watched and tended the smoldering “pit” to assure slow, even burning. About 2 weeks later, the process was completed. Fresh charcoal was raked out, partially cooled, and taken by wagon to the furnace.
With supplies of all the ingredients on hand, the founder directed the charging of the furnace. Workmen called “fillers” dumped approximately 15 bushels of charcoal into the tunnel head and then added 200 to 300 pounds of ore and several shovelsful of limestone. At approximately half-hour intervals day and night they repeated the process. Periodically, the founder tapped the furnace, draining off the molten iron and the slag residue. Two skilled “keepers” assisted and temporarily relieved the founder during the blast.
The quality of the iron produced as important as the amount. The owner-managers of Hopewell profited more from a high quality product that could be cast into saleable articles than they did from the less pure pig iron. The founder controlled quality by regulating the precise balance of the ingredients and the blast of air. When he tapped the furnace, the founder decided whether the molten iron met the demanding standers for casting. If it did, he rang the casthouse bell, calling in the skilled molders to lade the fiery liquid into their waiting sand molds. But if the flow contained too many impurities, it was run out into pig bars on the ground. The pigs were then shipped to a forge and hammered into usable shapes. The founder’s reputation, as well as his pay, was based on the percentage of high quality casting iron his furnace produced.
Molders too, were paid according to both the quality and the quantity \of their individual work. And they received higher wages for casting more intricate and difficult designs. The mold was made by compacting special sand around both halves of a wooden pattern. This required great care and precision, in order to keep stray grains of sand out of the pattern space.
Hopewell workers manufactured a wide variety of cookware and other iron products for a growing America. But stoves were the most frequently molded articles at Hopewell throughout most of its history. Many different types, including the famous “Franklin fireplace” for combined heating and cooking, were produced in their own casting patterns, which carried the retailers’ names rather than Hopewell’s. The retail dealer often handled the final assembling of the stoves. Among the customers for those stoves assembled at the furnace were the villagers themselves, who applied their earnings toward the purchase. By 1844, Hopewell molders had produced over 65,000 stoves for the homes of the land.
But Hopewell’s prosperity had reached its zenith by the mid-1830’s. Except for a brief boom during the Civil War, the rural manufacturing community, with its time-honored method of charcoal smelting, became increasingly obsolete. The expense of transporting goods to market posed formidable problems the village, which was located far from the expanding urban centers of distribution.
But the most serious problem was stemmed from the growth of modern industrial technology. The development of new smelting methods utilizing hotter-burning anthracite coal and heated air blasts meant that high quality iron could be produced more rapidly and with less expense. New ironworks were generally located near the growing urban markets, since they no longer required vast hardwood forests for fuel. One by one the rural charcoal furnaces closed down. Hopewell’s last attempt to remain competitive – the construction in 1853 of an anthracite furnace - failed to halt the decline. In 1883, the furnace "blew out" for the last time. And the remaining villagers turned their steps toward the cities in search of work – victims themselves of industrial progress, along with their sustaining furnace and an earlier, rural way of life.
The General park map handed out at the visitor center is available on the park's map webpage.For information about topographic maps, geologic maps, and geologic data sets, please see the geologic maps page.
A geology photo album for this park can be found here.For information on other photo collections featuring National Park geology, please see the Image Sources page.
Currently, we do not have a listing for a park-specific geoscience book. The park's geology may be described in regional or state geology texts.
Parks and Plates: The Geology of Our National Parks, Monuments & Seashores.
Lillie, Robert J., 2005.
W.W. Norton and Company.
9" x 10.75", paperback, 550 pages, full color throughout
The spectacular geology in our national parks provides the answers to many questions about the Earth. The answers can be appreciated through plate tectonics, an exciting way to understand the ongoing natural processes that sculpt our landscape. Parks and Plates is a visual and scientific voyage of discovery!
Ordering from your National Park Cooperative Associations' bookstores helps to support programs in the parks. Please visit the bookstore locator for park books and much more.
For information about permits that are required for conducting geologic research activities in National Parks, see the Permits Information page.
The NPS maintains a searchable data base of research needs that have been identified by parks.
A bibliography of geologic references is being prepared for each park through the Geologic Resources Evaluation Program (GRE). Please see the GRE website for more information and contacts.
NPS Geology and Soils PartnersAssociation of American State Geologists
Geological Society of America
Natural Resource Conservation Service - Soils
U.S. Geological Survey
General information about the park's education and intrepretive programs is available on the park's education webpage.For resources and information on teaching geology using National Park examples, see the Students & Teachers pages.