Overview of Alamo Archaeology

[TRK]

Oct 6, 2009 19:17:38 GMT -5 @powderkeg said:

"The palisade trench yielded a large number of artifacts related to the 1836 battle."

What are they and when can we see them?

I can answer the "What are they" part of your question, based on Jack D. Eaton, Excavations at the Alamo Shrine, Center for Archaeological Research, University of Texas at San Antonio, Special Report No. 10 (1980). Note, a section of the palisade trench near the church was just part of what this excavation unearthed, and the following is only my abstract of that portion of the report, which contains much more detailed information.

Ceramics: many fragments, including Majolica, Goliad, and Mocha ware; Pearlware; unslipped utility ware, etc.

Glass: A small number of fragments, including clear and tinted bottle and 1 fragment clear flat.

Chert: 1 Mission-type point and 1 small fragment of a gun flint of local chert

Metal: 34 iron fragments, 2 lead fragments, 11 square nails, misc. bits of metal, 1 brass buckle (fragment: from a belt or shoe(, 1 brass button, 1 iron musket sling swivel (identified as from a Brown Bess), 6 lead balls, 2 brass balls (i.e., spherical canister or grape shot), 2 spherical bronze shells, and 1 unidentified metal tool "with a screwdiver blade on one end and an attachment hole on the opposite end...Possibly this tool was attached to a gun carriage as part of the kit".

Bone: 1 button (1.47" diameter, one center hole; possibly a shirt button), 1 fragment of a cuff link

Building materials: 1 red ceramic floor tile, fragment, probably Spanish Colonial

Misc.: 12 fragments of charcoal, 4 mussel shells, 1 animal bone


A few notes:

The 2 solid bronze balls: one, 1.15" in diameter, was slightly flattened and had a deep hole in one side, possibly from the heat of firing; this may have been a canister shot. The other, 1.3" in diameter, may have been a grape, canister, or case shot.

The spherical shell fragments were determined to be from original shells measuring in diameter, respectively, 7.4" and 7.2" and may have been from the same shell.

[johnk]

Having visited the Alamo a number of times I was surprised to see level of Chapel wall at rear so low (the one ramp leads upto ).Now built up, but you can see original level....Must have left defenders exposed .

[Jake]

Almost a year since I retired from the Park Service, and I think this is the first time I've posted to the Forum since then. Don't let them tell you retirement is easy. Especially if you have a lifetime of research books and files, and a house not intended to hold that stuff in such a way that you can find things. And actually putting together a life on a whole different schedule, or lack thereof ...

Sorry to be gone so long, but -- well, take the excuses as read, ok?

So anyway, I'm reading through the Defenses essay in the middle of Zaboly's new book, Altar For Their Sons, and I'm finding references to the floor of the church having been x inches or feet lower then than now, and I'm recalling that I've seen this mentioned before, somewhere on the Forum, and it occurs to me: I don't know anything about a determination of the probable floor level of the church at the time of the Battle. So among the lot of yez, I figure there must be some expertise, or at least opinions, on this. And since JohnK has brought up the topic of the height of the back wall, I thought I'd butt in and ask about it.

[Allen Wiener]

Welcome back, Jake! Good to see you! You are preaching to the choir here as I "retired" 6 years ago and have not gotten started on 1% of all those things I was going to do. I've just been too busy!! I've been perusing Gary's new book, too, but I'm out of my depth on these questions. I have to say that I believe Gary's speculations about the appearance of the Alamo during the siege and battle are bound to raise a few eyebrows, but he makes some valid points regarding the evidence that he feels supports his vision. Naturally, I'd love to hear an archaeologist's point of view.

You've arrived back on the Forum just in time for the holidays, so let me take this opportunity to wish you a very happy one and a healthy, joyful new year!

Allen

[TRK]

Dec 19, 2011 21:41:48 GMT -5 Jake said:

So among the lot of yez, I figure there must be some expertise, or at least opinions, on this.

I don't recall a discussion on this forum as you described, Jake, and I did a search of the forum for likely keywords and came up empty. The following talks about the then/now level of the paving in front of the church:

Jack D. Eaton, "Excavations at the Alamo Shrine," CAH Special Report No. 10, 1980, p. 25, subsection "The Alamo Shrine Foundation":

"The base of the church wall, which rests upon the foundation, is 24 cm below the present flagstone paved surface. At this level, there appears to have been older flagstone paving possibly dating to the mission period. Some flagstone fragments were found to butt against the wall base. These earlier flagstones were possibly either part of an old walkway extending along the building wall or remnants of church courtyard paving."

Do you suppose it would have been a level grade from the paving stones at the front of the church to the floor of the church?

[Jake]

I have to say I've been avoiding signing back on because I just didn't have the space in the day to focus properly on Forum discussions. You guys are a tough mob to deal with, not for only half my attention.

I thought I remembered a statement by Mark Lemon about where the floor level was in re: the "window"/"doorway" into the MBC -- maybe not.

Yes, you're right, Jack's report has useful information in it about this. Barbara Meissner, in her report on the excavations inside the south transept of the church, said that the present paved floor surface at the center of the transepts was close to 25 cm above where Jack showed the paving at the exterior front of the church (Meissner, The Alamo Restoration and Conservation Project: Excavations at the South Transept, p. 101). However, we have no idea, far as I can tell, what the level of fill was inside the church as of 1835 when the cannon platform was built there.

Zaboly, on p. S22, note i, seems quite certain he knows what the floor level was in 1836, and I was wondering what his source of information was.

[Hollowhorn]

Hi Jake, good to see you posting on here, I've read your earlier posts on here & over on the ADP site & do appreciate your input. In the spirit of peace, love & goodwill to all men, help me out here:
God help me but I have to ask, it's bothered me for more years than I can remember & I've never gotten round to seeking the answer, till now. Why do we dig to reveal the past? What causes the build up of earth? Is it dust? Sinkage? The Alamo Church was only built around the 1780's, why has the ground in front of the church risen by so much in such a short time?
I know I can google, but I'd rather have a conversation.

[Allen Wiener]

Jake & Tom -- I also recall some thread (or perhaps a discussion somewhere else) with photos of excavations in the front of the church right up against the facade (on the south end of it, as I recall). Perhaps it was something Bruce Moses posted, but I cannot find it now either.

I'm away from home again for 2 weeks and have no books with me, including the new Zaboly book, so I can't answer Jake's question about Gary's sources; perhaps someone else who has the book can.

CORRECTION -- SEE MY NEXT POST WITH LINK TO THE THREAD I MENTIONED.

[Allen Wiener]

OK - here's the thread I was talking about; not sure if it answers Jake's question:

alamostudies.proboards.com/index.cgi?board=archaeology&action=display&thread=303

Note the following section:

"The principal discovery related to the exposed portions of the church footing and foundations was their massive size. The structure rests on the foundation just 24 cm below the current surface where the structure expands out to an estimated width of four feet. The foundation continues down to the caliche level some 84 centimeters below the current flagstone paving. Pieces of old flagstone observed near the juncture of the wall/foundation were thought to possibly date to the mission period.

"Eaton described the foundation wall and footing as follows:


"The foundation is constructed of large, load-bearing irregular stones and slabs which are roughly dressed on the facings and maintain fairly even coursing and alignment. These stones, which are generally around 10 to 20 cm in height and roughly 20 to 40 cm in length, are laid in rough horizontal coursing, using gray to occasionally pink sandlime mortar and many spalls to fill the larger mortar joints and to aid in setting the stones.

"The footing upon which the foundation wall rests is not as carefully built, and uses rubble stones and slabs set without coursing in yellowish sandlime mortar. It appears that the footing trench had been dug through the dark brown clay to the underlying base caliche, a depth of more than a meter. Stones and mortar had been placed into the trench to provide the footing. These were not merely dumped into the trench but were carefully set to bear the load. It seems possible that the footing had been installed some years prior to the construction of the foundation and might be the footing which supported the original stone church that subsequently collapsed.

"In building the church, there seem to have been three distinct construction phases (1) a foundation footing resting upon basal caliche which was placed within a footing trench; (2) a foundation wall installed upon this which rose above the old ground surface; and (3) the church walls, slightly less in thickness, which rest upon the foundation."

[Jake]

Hollowhorn -- most of the dirt on a site comes from human activity, digging foundations, ditches, wells, post holes, trash pits, graves, and everything else, all of which gets slowly spread across a site. But a surprising amount comes to a site in the form of blow-in, where the wind brings dust, dirt, and sand a little at a time but constantly. I worked on a mission in New Mexico that, when it was first excavated in the 1930s, was full of dirt and sand inside to a depth of about six feet, of which 3/4s was blow-in over a period of only about 100 years, and the rest came from the walls and flat earthen roof washing into the building.

Glen, thanks for the link back to Bruce's discussion of Eaton's work, and the subsequent discussion. The thing is, neither Eaton nor Meissner, who excavated inside the church, gives us any information on the level of the floor in 1835 when the cannon platform was built -- in fact, they can't, since we don't know how much fill was removed from inside the church and from the plaza in front during the construction of the plaza and the cleaning up of the church in the later 1800s.

However, maybe we can guess at the ca. 1835 ground level: Everett and Eastman show a fair amount of additional base below the carved faces of the bases of the pilasters on the front of the building, much more than is visible today, so you'd be tempted to say the ground was at least a foot lower as of the 1840s before the remains of the cannon platform were removed, but if you look at other pictures and the architectural drawings, and Eaton's excavation drawings on pl 57, you find that Eastman and Everett show the pilaster bases incorrectly - they never had any significant amount of additional flat base below the bottom rounded ridge across the bases, but they did have a narrow flat slab and then rough stonework below that. In fact, the photograph in Nelson's Illustrated History on p. 77 of his second revised, 1998, taken in the 1860s from the Grandjean Collection in the DRT Library shows the surface at the front is all the way down to the highest level shown by Eaton in his profile drawings, p. 56 and 57. In that 1860s photo you're looking at the top of what Eaton has labeled as "Level A white caliche."

Other photos from farther away or less focused give a visual impression of the bases of the pilasters that sort of look like the Eastman and Everett drawings, and suggest that they just simplified this lowest area to flat surfaces. The other Eastman drawing of the facade at a sort of 3/4 angle, on p. 76 of that same edition, supports this -- here, Eastman shows the left two pilaster bases simplified, and the right two with more detail that appears to show the same amount of pilaster base as in the 1860s photograph. Since no significant work on the plaza or inside the church had happened by then, I think we can assume this is also the approximate 1835 surface at the front of the church. However, inside the church would have had large amounts of blow-in fill and rubble from the weathering of the walls, as well as rubble from the knocking down of the ribs over the internal pilasters and the one section of roofing vault that actually got built over the apse end of the building. Presumably the building of the cannon position would have started from this roughly leveled mass of rubble, and it is unclear what depth that mass might have had. I would be tempted to suggest that the inside of the church was at least a foot higher than the surface outside at the front.

Wow, excuse me, I guess I got on a roll here.

[TRK]

Dec 20, 2011 18:02:41 GMT -5 Jake said:

Zaboly, on p. S22, note i, seems quite certain he knows what the floor level was in 1836, and I was wondering what his source of information was.

I think some of these guys have arrived at an approximation of the 1836 grade by analyzing the bases of the four columns as seen in the 1849 daguerreotype of the Alamo. www.cah.utexas.edu/pachyderm/alamo/ The assumption is that not much changed concerning the grade in front of the church from 1836 to 1849.

[Jake]

Yes, the level of the surface at the front in 1848-1860 seems to stay about the same and matches the surface found there by Eaton's work. I thought that the rubble level inside the church would make a difference to any thinking about the cannon platform there, but while I was sleeping last night (I do my best work sleeping -- I tried to convince my teachers of this in elementary school, but oddly, they wouldn't buy it) I realized that it is the height of the ground at the front door, where the ramp starts, that determines how high you can get at the back wall, where the platform is -- the level of rubble inside the church affects only how much work you have to do to build the platform to a given height. So it seems we've solved that problem, and I'd guess that Zaboly was looking at the same information and arriving at the same conclusions. About height, at least.

[Kevin Young]

Glad to have you back posting Jake!

[Hiram]

Oct 22, 2011 2:12:04 GMT -5 johnk said:

Having visited the Alamo a number of times I was surprised to see level of Chapel wall at rear so low (the one ramp leads upto ).Now built up, but you can see original level....Must have left defenders exposed .

John,

The external length of the church is about 106 feet, which makes the interior length somewhere around 100 feet. A functional ramp for an artillery battery needs about 6 feet of length for every foot of height of the firing platform. The east wall of the church was lowered by the Mexican army in 1835 to allow the ramp to be fully contained within the church.