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Underwater
Archaeology Branch
Division
of Archives & History
NC Department of Cultural Resources
Raleigh, NC
1979
Spring of 1977
Preliminary
investigations determine that the many obstructions on the river bottom
present a safety hazard to project participants and complicate survey
and recovery activities. Attempt
is made to remove as many as possible.
May,
1977
Unrelated to this project, the US
Army Corps of Engineers’ snag boat SNELL works its way up the
Roanoke removing trees and debris to clear river for navigation.
Underwater Archaeology Branch requests their help. Three days were
scheduled for the SNELL & its crew to assist in the clearing
effort.
Divers locate snags with a recording fathometer and cable each
one for removal by the SNELL. Before
lifting, each snag is carefully examined by divers to ensure that
any material that may have been thrown into the river from the
fort is not
disturbed. In spite
of the care taken, the first snag brings with it a wood and iron
wheel rim. The rim is
immediately retrieved but snagging operations are discontinued in
that area. Obstructions are removed from the area below Fort
Branch.
July, 1977
Less than two months after the snagging
operations, the survey and recovery project begins. First objective is a
comprehensive topographic survey of site.
This would generate data for compilation of a topographic map as
well as establish controls essential for production of magnetic profiles
of the site, bathymetric profiles, and the systematic recovery of
material from the river. Survey crews, working in temperatures often
exceeding 100 degrees Fahrenheit, establish baseline coordinates from
through the length of the earthworks and place stakes at 20-foot
intervals throughout the site. These
grid lines are carried over the bluff to the water’s edge and
continued across the river to establish points along the north bank so
that location of material and data removed from the river bottom can be
coordinated with the survey of the fort.
Since Rainbow Banks is nearly vertical, profiling the bluff
requires geometric survey techniques rather than conventional.
After survey markers are established on
both banks, magnetic and bathymetric profiles of the river are
conducted. From a small boat positioned by lines stretched along the
survey lanes running across the river, water depth and magnetic data is
collected every 20 feet. A
small recording fathometer determines water depth and a Geometrics
(801-G) proton precession magnetomer measured magnetic gradient.
These data are plotted on a site map and correlated with the
topographic map of the fort. The
information indicates a concentration of ferrous material below the
bluff west of the original entrance to the fort….where preliminary
investigations located cannon and gun carriage remains.
Researchers make final preparations for diving, excavation and
recovery operations.
July 18
Georgia
Pacific Corporation delivers a 40 x 100 ft. barge to the site on loan
for the project which will become a staging area for underwater work. A
stairway is constructed from the top of the bluff providing access for
equipment delivery such as scuba gear, compressors, temporary storage
tanks for artifacts and airlifts.
The search area is
approximately 90 x 110 feet and is divided into a grid of 18
five-foot-wide search lanes running parallel to the river bank.
Each lane is systematically searched.
Lack of visibility proves to be a serious limitation in dealing
with artifacts submerged beneath as much as one foot of sediment and
others hidden among debris and obstructions. Tactile examination and use
of underwater metal detectors are essential.
A tedious location, cataloguing, tagging and removal system is
followed. Artifacts are
placed into temporary wet storage on the barge and later transferred to
secure storage in the project camp at the top of the bluff where they
were photographed.
In addition to the
grid area, another area was determined to contain the largest
concentration of smaller artifacts.
Among other items, two brass cannon sights are discovered here.
Once lanes containing
cannon is cleared of artifacts and surface obstructions, a second
operation begins. Using airlifts, additional crews begin excavation in the
vicinity of the cannon. This
excavation serves two purposes: to
clear sediment from the guns so lifting straps can be secured and to
locate artifacts obscured from the metal detectors by masking the effect
of the iron cannon. In
addition to the two large cannon, three cannon carriages are found in
bottom sediment. Tons of
mud and sand must be air lifted away before these pieces can be
positively identified and prepared for recovery.
Exposing the carriages reveals that two
would mount what is identified as 6-pounder field pieces. The
third is an empty siege and garrison carriage similar to the one
recovered in 1972.
Sediment continually refills the bottom of the sizable depression
where the fieldpieces and empty carriage are located.
The small cannon and carriage are slung with lifting straps and
attached to sunken 55-gallon drums.
The drums are filled with air, lifting the items to the surface
where they are moved to more stable bottom before being raised during
the recovery operation. Large wheel rims are treated in the same manner.
This further clears the area surrounding the large cannon.
August 7
The
Army Reserve LCU 1476 arrives with a 20-ton capacity mobile crane.
Twenty-thousand pound capacity nylon straps are provided by the
US Army for slinging guns. The fabric straps are stronger than rope or
even steel cable and will not chafe or cut into the metal surface of the
cannon.
August 8
With all items
prepared for recovery and the crane on site and ready, a final briefing
session is held at 7:30 a.m. to insure coordination and a clear
understanding of the entire operation.
Law enforcement was on hand to provide crowd control (the
operation attracted much curiosity and interest) and safety. River traffic was appraised of the planned activities and the
operation was ready to begin.
With the cannon
already slung, diving operations required only the hook of the crane be
attached to the lifting straps with a final check to be certain they
were secure. As the crane
cleared the river bottom, a projectile was discovered under the
carriage! With no way of
knowing whether it was live, the operation was halted until the
projectile could be carefully removed and carried to the surface by a
standby safety diver.
The gun is lifted to
the surface, straps are inspected, and it is gently swung onto the LCU
and positioned onto automobile tires and oak blocks.
The gun is a 24-pound smoothbore Model 1819 on wooden siege and
garrison carriage. Once
aboard the LCU a continuous mist of fresh water is sprayed over it to
slow further deterioration. A
complete photo documentation is begun.
Divers return to the
river for one of the 6-pounder fieldpieces.
It is much lighter but requires even more care because a portion
of the wheel carriage is intact. Tires
and oak blocks are positioned so that no weight is placed on the fragile
wheel carriage once it is set onto the LCU.
Again, a continuous freshwater mist is used.
Once secured, the LCU
heads upriver for the boat landing at Hamilton.
The cannon are removed onto a trailer provided by the North
Carolina Department of Transportation (DOT) and returned to Fort Branch.
Public access is possible during documentation and disassembly
due to a sprinkler system set up in an open area near the top of the
bluff from which the guns were pushed 112 years earlier.
August 9
The third cannon
raising begins. The gun is a 4.62 inch rifle, Brooke type, manufactured
by the Tredagar Foundary at Richmond, Virginia in 1863.
It is mounted on a wooden siege and garrison carriage.
The second 6-pounder field gun mounted
on a wooden field carriage—almost identical to the one raised the day
before—is retrieved.
Following the recovery of the final two cannon, the empty siege
and garrison carriage and the loose wheel rims were brought aboard the
LCU. All is kept under a
freshwater spray, moved upriver to the landing at Hamilton and
transported to Fort Branch for temporary public display.
Documentation and dismounting are completed in a few days and
artifacts are placed in freshwater storage until preservations treatment
begins.
Final river bottom survey efforts use a
metal detector to help locate carriage parts that might have come loose
during the lifting operations.
This final examination also helps locate metal objects that were
masked from detection by the cannon’s iron mass.
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Fort
Restoration
