Memorandum for the Regional Director: Fort Marion Terreplein, and Rebuilding the Arch at Fort Matanzas


Material Information

Memorandum for the Regional Director: Fort Marion Terreplein, and Rebuilding the Arch at Fort Matanzas
Series Title:
Castillo de San Marcos Terreplein Project
Physical Description:
Edward D. Freeland
Publication Date:
Physical Location:
Folder: Prior excavations, research, & reports

Record Information

Source Institution:
University of Florida
Rights Management:
All applicable rights reserved by the source institution and holding location.
Resource Identifier:
97-3003; 93-3000; 94-3000
Castillo de San Marcos
System ID:

Full Text




EMORAi UDTJ L for the Regional Director
Attention: Regional Supervisor of Historic Sites.

Reference is made to Lr. Appleman's memorandum of July 3, l41l,
in which he requests a stmmamry of important ruins stabilization work at Forts marion and Latanzas. It is regretted that these data could not be submitted earlier, but vrith the loss of our guide project, Lr.
Lsanucy has been occupied for most of his time on public contact work.


The terreplein at Fort iarion is built upon a s&ie of coquina
(shellrock) arches. Fill was dumped between the of the
arches, then the entire surface was overlaid with tabby to a depth of six inches or more. In other words, the top or working surface of the
terreplein in Spanish days was a tabby mortar, reasonably smooth,
reasonably hard, that covered the entire too or terreplein of the fort.
(See photograph JA-123). Physical evidence indicates that there were no joints as such in the tabby, but it was a solid, unbroken surface.
This surface Tlms structurally important for several reasons: it
helped make the arches bombproof, it was a surface on which the guns could be manuevered with minimum difficulty, and it was a fairly effective watershed.

Over this tabby, which undoubtedly would not endure under the
grinding feet of the thousands of modern visitors, about 1890 the Wiar Department laid large concrete tile. Presumably the plan was to make a good walking surface, eliminate some of the dust hazard for the increasing number of visitors, and improve the drainage of the roof. in
later years, asphalt was poured over the tile on the section of roof over inhabited rooms. The roof was heterogenous, unattractive, and
not waterproof. Consequently, in order to ensure preservation of the
arches below, the National Park Service determined to construct a roof
that -:ould be waterproof, at least over the part of the fort that was
used for administration purposes. But as the engineers put their minds
to the problem, a more and more elaborate project developed.

Construction of the new terreplein surface involved first of all
removal of the 'War Department tile, then grading the old surface in

places where grading was needed for drainage. Six inches of concrete were laid over the entire top, thus completely covering the old tabby surface. Copper flashing was recessed into the parapet walls. Over the concrete base a waterproof membrance, consisting of 5-ply asphalt felt, was mopped on. On top of the membrance, hot asphalt grout was poured to a depth of about a half inch, and concrete tile approximately 18 inches square were lowered into the grout, which anchors then. There is considerable coquina aggregate in the makeup of the tile, so that there is a remote resemblance to the former tabby surface.

This work was justified on two counts: preservation of the fort by providing a waterproof roof, and insurance of visitor safety by providing a smooth walking surface, relatively free from sand and dust. If the original tabby had been left exposed, it would soon have disappeared under 20th century traffic.

In the light of Service policy that has recently been developed, it is regrettable that additional thought was not given to the project. Under different circumstances, another and more historically efficient solution to the preservation problem might have been found. The existing terreplein surface is necessarily at slightly different levels than the old one, due to adjustments for drainage. Its appearance is considerably different than that of the historic tabby, and the 18-inch tile do not give the effect of the seamless tabby. Admittedly, however, it -ould be extremely difficult to duplicate the old surface and still avoid expansion and drainage dangers.

Reference is made to the illustrated report of Junior Historical Technician Albert C. Janucy, "Terreplein Construction, Fort harion National monument: Notations on Its Original Character", and also to the plan entitled "Terreplein Paving", numbers iE-LAR 5300 and 5301, which gives constructional details of the new work.

The following photographs are enclosed:

A-123. The old tabby surface has been exposed, but is still
partly covered with the cushion of sand that was under the tile that was removed. The man at the left is undercutting the wall
to recess the copper flashing.

A-120. (Two prints) Here the top of an arch has been revealed.
Notice that there are three layers of tabby over the arch. This
tabby was the working surface and watershed of the terreplein. A
detailed explanation of this photograph is given on pp. 8-9 of
anucy's report "Terreplein Construction".

A-121. This view shows the 6-inch bed of concrete being laid.
This concrete was the base for the new work.

A-124. On top of the concrete bed, five thicknesses of asphalted
felt formed a waterproof membrane. Here the men are mopping on the


asphalt which sticks the saturated strips of felt to the concrete
and to each other.

A-122. Concrete tile, the walking surface, were placed over
the felt and asphalt membrane. Here the tile setters are placing
tile in sand over the fern room, which was not waterproofed. Over
all the rest of the fort, however, the tile was laid in a hot
asphalt grout, which securely anchored it to the surface.

If additional prints are required, please refer to the number of
the prints.


One of the major structural features at Fort i atanzas is the arch that is an integral part of the tower, or high section of the fort.

The location of the fort on a low, marshy island that lost its strategic importance by about 1800, was unfortunate for preservation of the structure. During a century of neglect, erosion undermined the fort to the point that the entire mass began to break apart, showing cracks a foot or more wide.

The fort was under War Department jurisdiction until its transfer to the Interior Department in 1933, mand about 1915 'the 'ar Department took steps to arrest further deterioration and pull the fort together. While detailed data on the preservation methods used are not available to the writer, it is evident that the method consisted of levelling and pulling together the portions Thich had settled, bolstering the foundations, and tying the structure together with iron rods. Undoubtedly some walls had to be partially demolished and rebuilt. Cracks which were not considered serious were repointed with concrete.

This preservation zork retained the significant lines of the fort, but the major cracks, particularly in the tower, were not sufficiently closed to true up the building, and the sides of the tower leaned outward. Courses of stone on the back wall of the tower were far from level, so that there was a visual effect of instability.

In addition, the arch in the tower was actually unsafe, so in 1939 the Service set about reconstructing this arch. Preliminary work had involved the building of a seawall of steel sheet piling around the structure to protect the site and the foundations. The high back wall of the tower was shored up with long saplings, and the face of the tower over the arch and then the arch itself were taken down stone by stone. In rebuilding the work, concrete mortar was used, and eleven l-t-inch steel tide rods were used to hold the structural members together. Considerable new rock was used in the reconstruction, but the major portion of the fort still consists of original masonry.


In order to waterproof the roof of the tower and protect the
masonry underneath, an asphalt surface was put down on the top deck of the tower. Coquina gravel was laid over the asphalt as a blend with the older work.

This construction work should not be regarded as a restoration, but entirely as preservation and insurance for visitor safety. The fort had been virtually rebuilt once before by the War Department, and a certain amount of physical evidence had been lost at that time. Source constructional records relating to the fort were not available, nor was it reasonable to suppose that they might be found in the near future. It was felt that the urgE~ay of the work d landed action for safety reasons, if for no other.

The preservation work was successful in that it has stabilized the general design of the structure ,ith minimum disturbance of constructional features. True, a better job in this respect might have been done by technicians and workmen especially trained in historical construction. The work is perhaps not entirely successful in that the new xork is vejr rough in comparison to the old, and for that reason, misleading as to the ability of the Spanish builder, since the average visitor is'not able to differentiate between the old and new work. Additional study of the fort may reveal the desirability of restoring the fort to the Doint that the rough, modern work will be hidden. For example, the entire fort at one time was stuccoed with ':hite lime plaster on the outside -- and possibly inside. A partial, or even complete replacement of the plaster would effectively conceal most anachronisms. Certainly, the fort is now structurally sound; the basic preservation work is done.

For constructional details, see plans entitled "Reconstruction of
Arch", Ni-iAT 1052 (two sheets).

A rare negative (IL-2) showing the fort as it appeared about 1914 is enclosed. It is urgently requested that this negative be returned as soon as possible, for it cannot be replaced. Two negatives (%Z-37
and IZ-38) of the fort as it looks today are enclosed, also with the request that the- be returned.

Edwasrd D. Freeland
Coordinating Superintendent
Enclosure 1294438
CC: Albert hnucr


..i. ort atwazas :aticmi vncueort, rsconstructin the arch.
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The vi to- : the south or. fot :m.11 of te car. Th arch

rods he! to hold the rebuilt structure together.

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