Bull's Island and Prallsville Mills
Hunterdon County, NJ.


Can be reached from Highway 29 about 3.5 miles north of Stockton.

From NYC take Turnpike south about 25 miles to I-287. Turn north on I-287 and go about 18 miles. Take US 202 southwest 26.5 miles to Route 29 on the east bank of the Delaware. Turn north and drive 5.5 miles to Bull's Island on the left. Parking is by the headquarters.


This island is part of the Delaware River floodplain, separated from the mainland by the Delaware River and Raritan Canal.  Bull's Island is an artificial island, created by the construction of the canal.

The stone here is from the Stockton Formation, better known as brownstone and is quarried locally. In the area are a few igneous intrusions of darker traprock, similar to those that formed the Watchungs and Cushetunk Mountain.


Bull's Island:

Opposite Bull's Island is the village of Raven Rock, location of the canal feeder's inlet. Here there are some 12 houses, the first built in 1782. The two and one half story, all-stone Saxton Tavern (now a private residence) was the farmhouse of the area's principal landholder, Nathanial Saxton. It served travelers on the old Frenchtown-Lambertville Road. (Patricia Reardon, "Architecture along the D&R Canal," New Jersey Outdoors, pp. 16-18.)

Richard Bull, one of the original owners, gave his name to the island and also to Bull's Creek, displaced by the canal, which separated it from the mainland.

1832 --  work on the D&R Canal was started.

1834 --  the Delaware River Dam, used to divert water from the river to the canal, was completed.


A mill was built here at what became Prallsville.

1794  -- John Prall bought the property.  He built a linseed oil mill on the property to process the flax plant.  The mill operated for 40 years.  Linseed oil is the base ingredient for paint and wood preservatives.

1834  -- opening of the Delaware & Raritan Canal.  In Prallsville, the Wichecheoke Creek flows into the Delaware and Raritan Canal.  Any overflow spills into the Delaware River. (Linda J. Barth 2002. Images of America: The Delaware and Raritan Canal. Charleston, SC: Arcadia Press.)

Just downstream is the Prallsville guard lock built to protect the canal against Delaware River flooding.

1834  -- closing of the linseed oil mill.  The building would be used as a plaster milling  factory.  Limestone was baked and then crushed with grist mill stones.

1860s  -- plaster milling stopped.

1874 --  the original gristmill burned, ignited by a spark from a passing steam engine on the B&D Railroad.

1877  --  a four-story gristmill was rebuilt on the old foundations. The seven buildings of the mill are unique in that they constitute the only historic multiple milling operation remaining in the state.

1890  -- the grain silo built. 


flood plain


A trail follows the edge of the canal from one end of the island to the other, a distance of a little over a mile. You can walk south three miles to Prallsville Mill.

Traveling westward the botanist comes to the bridge over the Delaware River. Bridge here built of limestone blocks. Growing in the tiny crevices are two interesting small ferns.

Dr. Patrick L. Cooney, Torrey Botanical Society and Philadelphia Botanical Club

Acer negundo (box elder)
Acer platanoides (Norway maple)
Acer rubrum (red maple)
Acer saccharinum (silver maple)
Acer saccharum (sugar maple)
Ailanthus altissima (tree-of-heaven)
Albizia julibrissin (silk tree; mimosa)
Betula nigra (river birch)
Carya sp. (hickory)
Catalpa bignonioides (southern catalpa)
Cornus florida (flowering dogwood) 5/22/97
Fagus grandifolia (American beech)
Fraxinus americana (white ash)
Fraxinus nigra (black ash)
Fraxinus pensylvanica (green ash)
Gleditsia triacanthos (honey locust)
Juglans nigra (black walnut) 5/22/97
Juniperus virginiana (red cedar)
Liquidambar styraciflua (sweetgum)
Liriodendron tulipifera (tulip tree) 5/22/97
Morus alba (white mulberry) 5/22/97
Picea abies (Norway spruce)
Picea pungens (Colorado blue spruce)
Pinus strobus (white pine)
Pinus sylvestris (Scots pine)
Platanus occidentalis (sycamore)
Prunus avium (sweet cherry)
Prunus serotina (black cherry) 5/22/97
Quercus rubra (red oak)
Quercus velutina (black oak)
Robinia pseudoacacia (black locust)
Salix nigra (black willow)
Salix sp. (willow)
Sassafras albidum (sassafras)
Taxus baccata (yew)
Thuja occidentalis (arbor vitae)
Tilia americana (American basswood)
Ulmus rubra (slippery elm)

Berberis thunbergii (Japanese barberry)
Cornus amomum (swamp dogwood) 6/30/97
Ligustrum sp. (privet) 5/22/97
Lindera benzoin (spicebush)
Lonicera morrowii (Morrow's honeysuckle) 5/22/97
Myrica pensylvanica (bayberry)
Pachysandra procumbens (pachysandra)
Rhus typhina (staghorn sumac)
Rosa multiflora (multiflora rose)
Rubus occidentalis (black raspberry)
Rubus phoenicolasius (wineberry)
Rubus sp. (blackberry) 5/22/97
Sambucus canadensis (common elderberry)
Spiraea alba var. latifolia (meadowsweet)
Staphylea trifolia (bladdernut)
Viburnum dentatum (arrowwood viburnum)
Vinca minor (periwinkle)
Wiegelia sp. (wiegelia) 5/22/97

Calystegia sepium (hedge bindweed)
Celastrus orbiculatus (Asiatic bittersweet)
Hedera helix (English ivy)
Humulus lupulus (common hop)
Lonicera japonica (Japanese honeysuckle) 6/30/97
Menispermum canadense (moonseed)
Mikania scandens? (climbing hempweed)
Parthenocissus quinquefolia (Virginia creeper)
Polygonum convolvulus (black bindweed) 6/30/97
Polygonum scandens (climbing false buckwheat)
Sicyos angulatus (one-seeded bur cucumber) 10/01/96
Smilax rotundifolia (round-leaved greenbrier)
Toxicodendron radicans (poison ivy)
Vitis riparia (riverbank grape vine)

Acalypha rhomboidea (three-seeded mercury)
Achillea millefolium (yarrow) 6/30/97
Alliaria petiolata (garlic mustard) 5/22/97 6/30/97
Allium vineale (field garlic) 6/30/97 soon
Amaranthus hybridus (slender amaranth)
Ambrosia artemisiifolia (common ragweed)
Ambrosia trifida (giant ragweed)
Anthriscus sylvestris (wild chervil) 5/22/97
Arabis glabra (tower mustard) 5/22/97
Arisaema triphyllum (jack-in-the-pulpit) 5/22/97
Artemisia vulgaris (common mugwort)
Asarum canadense (wild ginger) 5/22/97
Asclepias syriaca (common milkweed)
Aster cordifolius (heart-leaved aster) 10/01/96
Barbarea vulgaris (common wintercress) 5/22/97
Bidens sp. (beggar-ticks)
Boehmeria cylindrica (false nettle)
Brassica nigra? (black mustard?) 6/30/97
Capsella bursa-pastoris (shepherd's purse) 5/22/97
Centaurea maculosa (spotted knotweed) 6/30/97
Cerastium vulgatum (mouse-ear chickweed) 5/22/97 6/30/97
Chelidonium majus (celandine) 5/22/97 6/30/97
Chenopodium album (pigweed)
Chenopodium ambrosioides (Mexican tea) 10/01/96
Cichorium intybus (chicory) 6/30/97
Circaea lutetiana (enchanter's nightshade) 6/30/97
Cirsium arvense (Canada thistle) 6/30/97
Claytonia virginica (spring beauty) 5/22/97
Commelina communis (Asiatic dayflower)
Convolvulus spp. (morning glories)
Conyza canadensis (horseweed)
Datura stramonium (jimsonweed)
Daucus carota (Queen Anne's lace) 6/30/97 10/01/96
Desmodium sp. (tick trefoil)
Dianthus armeria (Deptford pink)
Dicentra cucullaria (Dutchman's breeches)
Duchesnea indica (barren strawberry) 5/22/97 6/30/97 & fr
Erigeron annuus (daisy fleabane) 6/30/97
Erigeron philadelphicus (common fleabane) 5/22/97 6/30/97
Erysimum cheiranthoides (treacle mustard) 6/30/97
Eupatorium dubium (Eastern joe-pye-weed)
Eupatorium fistulosum (trumpetweed) 6/30/97 soon
Eupatorium perfoliatum (boneset) 6/30/97 soon
Eupatorium rugosum (white snakeroot) 10/01/96
Euphorbia maculata (milk purslane)
Euphorbia nutans (upright spotted spurge)
Galinsoga quadriradiata (gallant soldiers) 6/30/97 10/01/96
Galium aparine (cleavers) 6/30/97 5/22/97
Geranium maculatum (wild geranium) 5/22/97
Geranium sibiricum (Siberian geranium)
Geranium pusillum (small-flowered cranes bill) 6/30/97
Geum laciniatum (rough avens) 6/30/97
Glechoma hederacea (gill over the ground) 5/22/97
Hemerocallis fulva (tawny day lily)
Hesperis matronalis (dame's rocket) 5/22/97 6/30/97
Hieracium caespitosum (field hawkweed) 5/22/97
Hosta sp. (hosta)
Hydrophyllum macrophyllum (large-leaved waterleaf) 5/22/97
Hypericum mutilum (dwarf St. Johnswort) 6/30/97
Hypericum perforatum (common St. Johnswort) 6/30/97
Impatiens capensis (orange jewelweed) 10/01/96
Impatiens pallida (yellow jewelweed) 10/01/96
Iris sp. (blue or yellow flag)
Lactuca biennis (tall blue lettuce)
Lactuca canadensis (wild lettuce)
Lactuca serriola (prickly lettuce)
Lamium purpureum (purple dead nettle) 5/22/97
Laportea canadensis (false nettle) 6/30/97
Lapsana communis (nipplewort) 6/30/97
Leonurus cardiaca (motherwort) 6/30/97
Lepidium virginianum (wild peppergrass) 5/22/97 6/30/97
Lespedeza capitata (round-headed bush clover)
Lindernia dubia (false pimpernel?) 6/30/97
Lobelia inflata (Indian tobacco) 10/01/96
Lobelia spicata (spiked lobelia) 6/30/97
Ludwigia palustris (marsh purslane)
Lysimachia ciliata (fringed loosestrife) 6/30/97
Lysimachia nummularia (moneywort)
Lythrum salicaria (purple loosestrife) 6/30/97 10/01/96
Matricaria matricarioides (pineapple weed) 5/22/97 6/30/97
Medicago lupulina (black medick) 522/97 6/30/97
Melilotus alba (white sweet clover) 6/30/97
Melilotus officinalis (yellow sweet clover) 6/30/97
Mimulus ringens (monkey flower) 6/30/97
Mirabilis nyctaginea (wild four o'clock)
Mollugo verticillata? (carpetweed) 6/30/97
Monarda fistulosa (wild bergamot)
Myosotis laxa (smaller forget-me-not) 5/22/97
Myosotis scorpioides (forget-me-not) 6/30/97 10/01/96
Oenothera biennis (common evening primrose) 10/01/96
Ornithogallum umbellatum (star of Bethlehem) 5/22/97
Osmorhiza claytoniana (sweet cicely) 5/22/97
Osmorhiza longistylis (aniseroot) 5/22/97
Oxalis stricta (yellow wood sorrel) 5/22/97 6/30/97 10/01/96
Oxalis violacea (violet wood sorrel) 5/22/97
Perilla frutescens (perilla mint)
Physalis heterophylla (clammy ground cherry) 10/01/96 in fruit
Phytolacca americana (pokeweed) 6/30/97
Pilea pumila (clearweed)
Plantago lanceolata (English plantain) 5/22/97 6/30/97
Plantago major (common plantain) 6/30/97
Podophyllum peltatum (may apple) 5/22/97
Polygonatum biflorum (true Solomon's seal) 5/22/97
Polygonum cespitosum (cespitose knotweed) 6/30/97 10/01/96
Polygonum cuspidatum (Japanese knotweed)
Polygonum lapathifolium (nodding knotweed) 10/01/96
Polygonum pensylvanicum (pink knotweed) 10/01/96
Polygonum virginianum (jumpseed)
Polygonum sp. (tearthumb) 10/01/96
Potentilla argentea (silvery cinquefoil) 6/30/97
Potentilla canadensis (dwarf cinquefoil) 5/22/97
Potentilla norvegica (rough cinquefoil) 6/30/97
Potentilla recta (rough-fruited cinquefoil) 6/30/97
Potentilla simplex (common cinquefoil) 5/22/97
Prenanthes altissima (tall white lettuce)
Ranunculus abortivus (small-flowered crowfoot) 5/22/97
Ranunculus bulbosus (bulbous buttercup) 5/22/97 6/30/97
Ranunculus repens (creeping buttercup) 5/22/97
Ratibida pinnata (grayheaded coneflower)
Rudbeckia hirta v pulcherrima (black-eyed Susan)
Rumex acetosella (field sorrel) 5/22/97
Rumex crispus (curled dock)
Rumex obtusifolius (broad-leaved dock)
Rumex orbiculatus? (water dock?) 5/22/97
Sagina sp. (pearlwort) 6/30/97
Saururus cernuus (lizard's tail)
Scleranthus annuus (knawel) 6/30/97
Scrophularia lanceolata (hare figwort) 5/22/97 6/30/97
Silene latifolia (white campion) 5/22/97 6/30/97
Sisymbrium altissimum (tumble mustard) 5/22/97
Smilacina racemosa (false Solomon's seal) 5/22/97
Solidago caesia (blue-stem goldenrod)
Solidago spp. (goldenrod)
Stellaria pubera ? (great chickweed) 6/30/97
Taraxacum officinale (dandelion) 5/22/97 6/30/97
Thlaspi arvense (field pennycress) 5/22/97
Trifolium pratense (red clover)
Trifolium repens (white clover) 5/22/97 6/30/97
Triodanis perfoliata (Venus's looking glass) 6/30/97
Urtica dioica (stinging nettle)
Urtica dioica var. procera (tall nettle) 5/22/97
Verbascum thapsus (mullein)
Verbena hastata (blue vervain) 6/30/97
Verbena urticifolia (white vervain)
Verbesina alternifolia (wingstem)
Veronica officinalis (common speedwell)
Veronica persica (Persian speedwell) 6/30/97
Veronica sp. (speedwell) 6/30/97
Vicia cracca (crown vetch) 6/30/97
Viola sororia (common blue violet) 5/22/97
Viola sororia var. (confederate violet) 5/22/97
Zizia aurea (golden alexanders) 5/22/97

Carex intumescens or grayii?
Carex laxiflora group (sack sedge)

Juncus tenuis (path rush)

Anthoxanthum odoratum (sweet vernal grass)
Bromus inermis (smooth brome grass)
Bromus tectorum (downy brome grass) 5/22/97
Dactylis glomeratus (orchard grass)
Digitaria sp. (crab grass)
Echinochloa crus-galli (barnyard grass)
Elymus hystrix (bottle brush grass)
Festuca elatior (meadow fescue grass)
Leptoloma cognatum (fall witch grass)
Lolium perenne (English rye grass)
Microstegium vimineum (Japanese stilt grass)
Panicum clandestinum (deer tongue grass)
Paspalum sp. (paspalum grass)
Phleum pratense (timothy grass)
Poa annua (annual bluegrass) 5/22/97
Poa compressa (Canada bluegrass) 6/30/97
Poa pratensis (Kentucky bluegrass) 5/22/97
Secale cereale (wild rye grass)
Tridens flavus (purpletop grass)
Triticum aestivum (wheat)

Ferns and Fern Allies:
Equisetum arvense (field horsetail)
Equisetum hyemale (common scouring rush)
Asplenium ruta-muraria (wall rue fern)
Athyrium thelypteroides (silvery glade fern)
Dennstaedtia punctilobula (hay-scented fern)
Matteuccia struthiopteris (ostrich fern)
Onoclea sensibilis (sensitive fern)
Pellaea atropurpurea (purple-stemmed cliff brake) (smooth form)
Polystichum acrostichoides (Christmas fern)
Woodsia obtusa (blunt-lobed woodsia)

plants not found at Bull's Island

Arabis glabra (tower mustard) 5/22/97
Artemisia vulgaris (common mugwort)
Asclepias syriaca (common milkweed)
Athyrium thelypteroides (silvery glade fern)
Berberis thunbergii (Japanese barberry)
Capsella bursa-pastoris (shepherd's purse) 5/22/97
Centaurea sp. (knapweed)
Chenopodium album (pigweed)
Dennstaedtia punctilobula (hay-scented fern)
Equisetum arvense (field horsetail)
Eupatorium dubium (eastern joe-pye-weed)
Hieracium cespitosum (king devil hawkweed) 5/22/97
Hydrangea paniculata (wild hydrangea?)
Lepidium virginianum (wild peppergrass) 5/22/97
Liquidambar styraciflua (sweetgum)
Liriodendron tulipifera (tulip tree) 5/22/97
Lolium sp. (rye grass)
Lonicera morrowii (morrow's honeysuckle) 5/22/97
Matricaria matricarioides (pineapple weed) 5/22/97
Medicago  lupulina (black medick) 5/22/97
Myrica pensylvanica (bayberry)
Onoclea sensibilis (sensitive fern)
Plantago lanceolata (English plantain) 5/22/97
Polygonatum sp. (giant Solomon's seal)
Rhus typhina (staghorn sumac)
Rubus sp. (blackberry) 5/22/97
Rumex orbiculatus (water dock?) 5/22/97
Salix sp. (willow)
Scrophularia lanceolata (hare figwort) 5/22/97
Silene alba (white campion) 5/22/97
Taxus baccata (yew)
Wiegelia sp. (wiegelia) 5/22/97
vetch chamomile? 5/22/97