Tidbury Causeway and Sawmill Site Portion of the Mill Seat

Hunn Town

The present Tidbury Branch causeway is considerably wider than the old mill dam, and probably is not as high. The dam was converted into a roadway after 1813 and before 1857, probably about 1820. Over the years, the causeway has settled, requiring constant repair. In its present form, the road and bridge dates from about 1925.

The present alignment of the causeway probably was established with construction of the mill dam under the 1793 Act In order to have supplied the forge raceway, the original dam would have been about six feet higher than the present causeway. By 1813, when it was described in a deed, the pool elevation was down to about four or five feet, which could have been impounded by the present causeway.

Tidbury Branch originally flowed along the south bank of the valley (FIGURE 5), but was diverted to the present bridge sometime in the nineteenth century. The St Jones formerly came very close to the bridge, before the Corps of Engineers cut a canal farther to the east At the north end of the dam was the sawmill site, known from a specific location identified in the 1813 survey (FIGURE 11).

Downstream from the bridge at extreme low tides, it was possible to see a large timber-cribbed gravel causeway, which was the link between the Camden Road and Lebanon on the 1806 map (PLATE 14). It is broken by the present branch, but this obviously was not originally intended as a channel. Nearer the river, an upright board bulkhead appeared to mark some sort of slip or channel. These features were precisely measured by a Delaware Department of Transportation survey crew (FIGURE 11). Local legend states that these structures in the water are remains of the Hunns' nail factory. Timber preservation in the marsh is excellent; the side timbers of the earthen structure can be traced up to the high ground.

North of the bridge, the causeway slopes uphill to meet the natural hill at about elevation 17 feet. The documented point that was north of the old sawmill is on the causeway, but on firmer ground than most of the dam.

The first effort to find the sawmill was a hand-dug trench, ER 40 (FIGURE 11), that was two feet wide and parallel to the roadway in the valley. The trench was dug to a depth of a foot through natural- looking yellow and gray sand. It was later intersected by a Gradall trench to a depth of five feet with similar results. Although this should be pan of the sawmill, there was no evidence that the soil" had ever been disturbed. Probing with a steel rod nearby failed to reveal any evidence of timber or brickwork.

At the bridge, adjacent to its northeast abutment, the authors noticed a pile of barnacle-covered handmade brick, ER 10, that appeared to be lying in an orderly fashion on the gravel. Such a quantity of brick of that age, in some apparent order, required further investigation. Because the deposit could be observed only at very low water, the investigators went back to other work and waited for an opportune low tide. A Gradall was used to cut a hole, about four feet square, into the marsh mud behind where the bricks had been observed. The cut went into the bank of the causeway, which proved to be resting on more black marsh mud. Then it was time to wait for a low tide.

Waiting for a low tide, the authors observed a phenomenon that must have had an effect on the navigation of the Saint Jones. The tides in the river do not coordinate with the tides in Delaware Bay at Bowers. Sometimes the low tide at Lebanon is two hours later than the low tide at Bowers, but more frequently there is no really low tide. Rather than a twelve-hour cycle, the river rises and falls at its own pace, which varies. If low tide occurs when the tide is low at Bowers, the submerged features will show; otherwise the river will drop to a half tide and then refill. At low water, Tidbury Branch is still pouring out the bridge; if it is at all swollen by rain, Tidbury will be a foot or so higher above the bridge.

Since the investigations required extreme low water, the wait continued until the river finally dropped on July 15. Standing in the hole, it was possible to probe with a rod deep into the bank and into the muck over an area about ten feet long. No structural remains were found in this probing. On the bank, the bricks were examined closely and proved to be lying in a flat pattern, but not mortared. Rod probing of this entire area failed to bring up evidence of a structure. The authors then probed in the area west of the earthen causeway structure, to see if any timber structure had survived in the space between the two earthworks. No additional structures were uncovered.

If the sawmill stood in the higher sandy soil, timber preservation should not be expected; no remains were found in the marsh muck area, which has demonstrated good timber preservation.