The Fiske Center Blog

Weblog for the Fiske Center for Archaeological Research at the University of Massachusetts Boston.

October 28, 2015
by Dennis Piechota

The tale of the tile: recovered from the Gore Place greenhouse

Gore Place, in Waltham, Massachusetts, was the home to former Massachusetts Governor and US Senator Christopher Gore and his wife Rebecca from 1791 to 1834. The Gores were responsible for constructing the standing mansion house (ca. 1806) as well as a greenhouse and fruit wall that are no longer extant. The Gore Place Society, which now owns the property, has embarked on a long-term project to understand the agricultural and horticultural landscape around the house. This research included archaeological excavations at the site of the 1806 greenhouse, which recovered this partial marble tile in addition to many other building materials and artifacts that were used in the greenhouse.


Gore Place CXT 953 Lot AF 2012
Marble Tile Fragment
32.5 cm x 22.7 cm x 5.8 cm
Tale of Tile Image Annotated


Before treatment the tile fragment, shown above after light cleaning, was examined and found to be encrusted on its top surface with soil matrix, mortar (1) and an unknown dark charred organic accretion (2) located in a shallow channel (1.5-2.0 cm wide) (3) parallel with and just inside of the mortar accretion (5 cm wide).


One well-finished, manufactured edge is present and visible at the bottom edge of the photograph (4). Two other edges were crudely finished and mortared at right angles to the manufactured edge. The fourth edge, shown at the top of the photograph, is a relatively modern break surface and follows what may have been an old crack. The gray color of the marble at the break surface and the charred organics suggests the tile was burned (5). The thick residue of charred organic matter covering the marble in a line just inside of the mortared edge also suggests exposure to fire. This thicker accretion may have been protected from complete combustion by contact with a lost architectural element. That and the presence of a mortar line residue suggests that the edge of an architectural element abutted the tile along that line.


The face shows extensive wear and organic acid-erosion except at the alkaline mortar-protected finished edge. While the exposed surfaces are deeply eroded the original manufactured saw-cut pattern is still visible on the protected edge in a corner where the mortar has recently been lost (6). The erosion, over most of the unprotected face, takes the form of a very uniform undulating pattern of shallow cups and appears at first to be deliberate (3). Under low power microscopy the erosion shows extensive chemical attack and suggests instead that this was not a manufactured pattern. In fact it is more consistent with a kind of inter-crystalline acid attack that was slow acting, evenly spread over the surface and longterm. In this context the source of the acid was probably contact with a stable covering of moss. It’s acid secreting roots would be dense and persistent enough under constantly damp conditions of a greenhouse to develop this type of delicate low-energy acid erosion pattern.


Away from the mortared edge (5) this crenellated erosion pattern appears to have been mechanically worn down, possibly by occasional foot traffic more towards the center of the tile than its edge. The face of the tile also shows scraping losses where a pointed tool as well as a broad scraping tool had both been used on the surface at least seven times. This action with the foot traffic probably destroyed or prevented the acid-erosion pattern from developing near the tile’s center. The scraping marks may have been left by periodic cleaning action perhaps aimed at removing what could have been a thick mat of moss.


The reverse face of the tile is unfinished and uniformly coated with thick mortar. The mortar is extensively cracked due either to traction (shrinkage while under tension) during its initial set or due to exposure to high temperature. The undulating decay pattern is not present on the reverse side i.e. there is no inter-crystalline decay of the marble perhaps because it was isolated from the elements of the exposed side and because it was protected by the alkaline mortar which would neutralize organic plant acids.


This examination suggests the following possible sequence of use, re-purposing and discard:


– Manufactured as a larger marble slab

-Two edges were roughly re-cut perhaps to re-purpose the slab for use in a greenhouse as a drain liner and probably installed horizontally

– During an extended period of use the marble surface was eroded by a live mossy root mass

– Periodically the surface was mechanically cleaned and exposed foot traffic

– It was then exposed to a fire that caused charring of the mossy root mass in place on the marble. The high temperature also turned the surface gray wherever it was not protected by the thick lime-based mortar

– The tile was buried until 2012 in a non-acid soil containing fire-related ash that helped to preserve the original acid erosion pattern.



The above was developed from the Fiske Center conservation treatment report, C-00667.


Dennis Piechota


October 26, 2015

For more information about the greenhouse excavations, you can download the full technical reports from

July 16, 2015
by Fiske Center

A Whimsical Find

Dog foot print on a handmade brick

Dog foot print on a handmade brick

The top 40 centimeters in our first unit against the house at Gore Place have been full of demolition debris — brick, mortar, building stone, slate, and marble tile fragments. We don’t save all of that architectural material, but we do look at the pieces to see if there is anything distinctive that would merit saving any as a sample. We were rewarded yesterday by a dog footprint on one of the broken bricks from the rubble! A footprint like this is made when an animal walks over the wet bricks, at the manufacturing site, before they have been fired. This find doesn’t shed any light on the questions that we are trying to answer about Gore Place, but it’s a cool and very evocative bit from the past, and the first find of this type by anyone on the crew.

July 14, 2015
by Fiske Center

New Territory at Gore Place

Kellie and Justin opening the first of two planned units against the north face of the building.

Kellie and Justin opening the first of two planned units against the north face of the building.

We are doing a short, 3 week project at Gore Place this summer, a historic property in Waltham, Massachusetts, where we have done a number of previous seasons of research on the formal and agricultural landscape, including excavating the remains of an early 19th-century greenhouse. During our first week and a half, we have been following up on earlier work in the drive circle. Yesterday, we started exploratory work in a totally new area, against the historic house. We are looking for evidence of cellar and ground floor entrances that no longer exist, but since it is a new area, do not know what to expect!

July 11, 2012
by Fiske Center

After the Excavation: Pollen Analysis

One of the common adages in archaeology is that every day spent in the field leads to three or five days of work in the lab. Well, what are we doing for all of that time in the lab?

Below, Allison Conner, one of the students who worked on the Gore Place project, explains what she will be working on over the coming months.

The field school is over but for many of us our work has just begun. Over the course of our five week excavation at Gore Place we collected over 20 pollen samples from various locations across the site in the hope that they could tell us what sort of plants were being grown in and around the greenhouse. Pollen can be a tricky artifact to deal with archaeologically, because modern pollen and archaeological pollen are indistinguishable from one another. That’s because pollen doesn’t degrade in the same highly visible and obvious way that say a metal artifact rusts when it decays. Hence, pollen samples must be handled very deliberately.

David Landon and Allison Conner collecting a pollen sample.

In the field, pollen samples must be taken carefully to avoid contamination from modern pollen rain. Pollen rain is the cloud of airborne pollen that showers down from modern plant life. The yellow-green film of pollen which covers car windshields and pools of water when pine trees pollenate is one of the most obvious examples of pollen rain. To avoid getting that modern pollen rain in our soil samples several precautions must be taken when gathering pollen samples. The first is to never sample when it’s windy. The second is to maintain as sterile an environment as possible while sampling.

The first step of pollen sampling is to use a trowel to clean off the surface of the wall or floor that you will be sampling from. This scrapes off most of the modern pollen which has fallen on the surface since it has been exposed. The second step is to clean the trowel using distilled water and sterile wipes in order to wipe off the modern pollen on your tool and get as sterile a surface a possible for collection. The third step is to use your freshly cleaned trowel to collect your sample. To process a pollen sample you need at least 30 grams of soil which is collected and placed in a whirlpak bag. Whirlpaks are specially-made collection bags which are completely sterile on the inside and sealed until opened by the archaeologist taking the sample. Once the bag is filled with the sample it is sealed and labeled with the location and number of the sample.

Preparing to the the samples; note the distilled water and labelled whirlpacks.

Pollen samples are best taken from closed archaeological features like buried floors and pits. Pollen samples can also be taken at set increments along the wall of an excavation unit. When taking samples this way it is important to start at the bottom and work your way up so that lower samples are not contaminated from the material above. Though we did not use this method at Gore Place, pollen samples can also be taken from large soil cores driven into the ground.

Once a group of soil samples have been collected, they are refrigerated until they can be processed. Refrigeration prevents the pollen from further decomposing. This is an important step since pollen processing is time consuming and only a maximum of eight samples can be processed at a time. Pollen processing takes a minimum of two days but usually a total of three days to complete. The first day involves using chemicals like hydrofluoric acid and hydrochloric acid to dissolve the minerals and silicon in the soil. On the second day of processing, the chemicals used to dissolve the soil are decanted off and the sample is washed to neutral. The third day of processing involves using several acids to decompose the non-pollen organic materials left in the soil sample. Once that process is completed you are left with a small vial of liquid sample which has the same look and consistency as muddy water.

Cleaning the trowel between samples.

Now that the sample has been processed it can be scanned for pollen grains. A drop of sample solution is placed on a microscope slide with a drop of glycerol, covered with a coverslip and scanned under a 400x dissecting microscope. The glycerol allows the pollen grains to “swim” on the sample so that a gentle tap on the slide will roll the grains and give the scanner a different view of the pollen in question to help aid in identification. As the slide is scanned pollen grains are identified as specifically as possible and counted until the total number of pollen reaches at least 300.

Typically, although with several exceptions, most pollen can only be confidently identified to the Family level. The three pictures of Rosaceae pollen below should give you a hint as to why that’s the case. All three represent very different Genus within the same family, and all three look very similar. Could you tell them apart if you saw them all together on the same slide? Remember also, that individual pollen grains vary in size and appearance and that the pollen grains from soil samples are often broken or degraded in some way.

Thus the results of pollen analysis are often rather general identifications. However, my goal in examining the pollen samples from Gore Place is to identify at least the Rosaceae family to the Genus level so that we can get a more specific sense of what was grown around the Gore Place greenhouse. Even general Family identifications can be extremely valuable as they give us a list of possible plants which can be narrowed down through documentary research.

The Gore samples are currently sitting in the paleoethnobotany lab refrigerator at the Fiske Center awaiting processing and scanning.

–Allison Conner

July 2, 2012
by Sean Romo

The End of Excavations… For Now

The Crew

Time flies when you’re digging, and on Friday our summer excavations at Gore Place came to a close. After five weeks, we’ve excavated 13 units across three trenches, and moved a small mountain of dirt across the site. So what have we learned? For starters, we know that the greenhouse was not simply demolished. The destruction layers associated with the greenhouse were confined to a relatively small area, and were comprised mostly of brick, mortar, plaster, and stone. We found few artifacts in these deposits, and almost everything was highly fragmented; there were only a few whole bricks recovered, for example. Had the greenhouse just been knocked over and buried, we should have found not only more rubble than we did, but more intact bricks or wall segments. Additionally, there should have been a far greater amount of glass, since greenhouses required large windows along the southern wall to facilitate plant growth. Thus, our excavations point to a more controlled deconstruction of the greenhouse, with building materials and tools carefully removed (leaving little for the archaeologists!). Around the same time as this greenhouse was dismantled, we know that the grapery greenhouse was being expanded, and it is possible that our missing windows and bricks were incorporated into that structure.

Even with few artifacts, we were still able to learn more about the greenhouse’s appearance and lifespan. The discovery of many marble tile fragments corroborates the idea that the building was similar to the Gore mansion, and that it was at least partially a public space. There would be no reason to floor a purely utilitarian space with expensive marble tiles, but they would make sense if Gore wanted to show off the greenhouse to his friends. The northern and eastern foundations of the building were partially intact and made of stone. Prior to demolition, these stones were likely supported brick walls. The south wall has been almost completely destroyed, but the rubble layer has an abrupt and very distinct edge where we believe the wall once was. Taken together with data from the 2008 excavations, we know that the greenhouse measured 40-45 feet long and 14 feet wide. The ceramics from the building all date to before 1830-1840, reinforcing documentary evidence which suggests the greenhouse was demolished between 1840 and 1850, and possibly even earlier.

Here you can see the north wall (the line of stones at the top) and where the south wall was (just behind where the stack of bricks is at the bottom)

This project has also turned up tantalizing hints about how the space around the greenhouse was used. A nearby cobble surface may have served as an outdoor workspace for the building, and a brick and stone wall extending south from the greenhouse may have formed an enclosure separating different yard spaces. The last trench we opened was centered on an intriguing circular feature identified during the Ground Penetrating Radar (GPR) survey, and it turned out that the feature was a set of gravel paths. Below these walkways we found several sets of small planting holes, and both the paths and planting holes may have been different iterations of a formal garden space.

Danielle cleaning around the cobble surface

I think that everyone would agree that excavating at Gore Place this summer has been a very rewarding experience, but the work is far from over. The next phase of the project is to clean and identify the artifacts we’ve recovered, and analyze the soil and pollen samples we took on site. Studying these items will hopefully help to clear up the many questions that remain after this summer’s work. For example, we still don’t know what was grown in the greenhouse, which pollen analyses may elucidate. It is also unclear how many of the features of the site, such as the gravel paths and the cobble surface, relate to the greenhouse. Lab-based analysis of artifacts, pollen and excavation notes may lead us to concrete answers. Or, as often happens in archaeology, to more questions. Either way, there will be more Gore Place news coming – we’re planning more excavations for the fall, so stay tuned!

It can be difficult to see, but if you look closely you'll notice a large amount of gravel running top to bottom (North-South) in this unit. Without GPR, we may never have found this feature!

The wall extending off the SE corner of the greenhouse. It is unclear if it is contemporary with the greenhouse, although it is on the same orientation.

June 23, 2012
by Fiske Center

Hass Woods Students visit Gore Place

On Thursday afternoon we took a little break from the steamy woods of Grafton to visit the other UMASS field school at Gore Place in Waltham, MA. Drs. David Landon and Christa Beranek from the Fiske Center took some time to show us around the property, a 19th century rural gentleman’s farm and estate, and then showed us their excavations of the greenhouse and one of the gardens on the property. It was really neat to see the difference between the two farms, Sarah Boston’s and Gore Place, which were occupied during the same time period, in the early 19th century. Thanks for the hospitality guys!

Dr. Dave Landon gives the Hass Woods field school students a tour of Gore Place

Dr. Landon explains the architectural features of the greenhouse evident from the findings inside a recent excavation trench.

by Heather Law Pezzarossi

June 20, 2012
by Nadia Kline

Trenches galore at Gore Place

As week four at Gore Place continues, we find ourselves presented with yet another puzzle to sort out in the new trench. Last week we opened up a 2×8 trench comprising four units just to the east of our original trench. Shortly after removing the gravel and sod from the surface and shovel scraping down past a superficial gravel layer, a large patch of sandy soil in one of the units emerged and as more soil was removed from the rest of the trench, more of the sandy patch was revealed. It is now visible through nearly the entire length of the trench, save the easternmost unit, which has presented us with a nice cobbled surface. This seems to have been set up at the bottom of a slope made from the sandy soil, perhaps to hide it from the view of the Gores’ visitors as they came up the driveway. It’s possible that it was a work surface that they may have wanted to make as discreet as possible. Regardless, it’s clear that this surface was intentionally prepared when compared to the messy layer of destruction rubble in the westernmost unit, which was filled with broken mortar, brick, and rock.

Elizabeth and Danielle mapping the cobble surface.

Speaking of the westernmost unit, excavation has revealed a complicated set of soil changes intermingling with one another throughout the 2×2 square. This unit began with two separate soil contexts bisecting the space from east to west. The southern context revealed the continuation of the sandy patch found in the units to the east, while the northern context contained the rubble layer. At the bottom of the rubble, yet another context has appeared. Within that context, a large metal band of a circular shape has been excavated and looks to be a barrel hoop. More digging will doubtless provide the answers to our questions about this unit.

In the adjacent unit, Alison and Julia have been working hard to uncover a wall foundation running north to south made of brick and mortar with a base of field stones and flanked on either side by builder’s trenches. At first we thought that this might be a 20th century structure from the estate’s days as a golf course, but now it seems like it might actually be a 19th century wall after all, though most likely later in date than the original greenhouse. This unit has turned up numerous artifacts including a beautiful piece of 19th century factory made slipware.  Yesterday, we opened a unit off of the south wall of this unit to  follow the wall foundation out a little more. So far everything looks great!

Everyone at work in the second trench.

In addition, we’ve just opened a 2×4 trench to the southeast of the second trench where the GPR has indicated that a bulls-eye like structure should be located. The only way to found out exactly what lies beneath is to move some dirt. In the words of one of our fearless leaders Dave Landon, onward and downward!

June 13, 2012
by daniellecathcart001


Hi Folks,

Settle in, because we have a bunch of new developments to share with you.  In the short time we’ve been digging at Gore Place, it’s probably not too much of an exaggeration to say we’ve moved close to a metric ton of dirt.  We’ve answered a number of important questions, but of course have encountered some unexpected surprises resulting in even more questions.  Our strategy of excavating large open areas has proven very successful.   Using a system of alphabetically labeled Lots, we are able to visualize the extent of different soil deposits and how they relate to each other.  As you can see in the post below, we’ve opened two trenches placed strategically to reveal the northern, southern, and eastern walls of the greenhouse.  Each trench is sub-divided into 2×2 meter excavation units so we can maintain a greater degree of control over artifact densities and soil stratigraphy.

  In our initial 2×10 meter trench, below the topsoil, we came down to a substantial layer of rubble that accumulated within and spread outside the greenhouse during the demolition event.  This deposit contained predominately architectural debris including brick and mortar fragments, window glass, and nails along with small pieces of decorated and plain ceramics, bottle glass, buttons, and animal bones.  Once the thick rubble layer had been removed, we discovered what remains of the northern and southern walls of the greenhouse, characterized by large stones, brick, and mortar that run east-west through two of the units.  These walls 14 feet apart and appear to have been set into the subsoil.  This means that when the greenhouse was built, a large amount of dirt was excavated from the construction site, some of which was redeposited around the building perhaps in an effort to even out the surrounding landscape and create level workspaces.  Additionally, we uncovered a very large dark brown, charcoal-rich pit feature that sits immediately adjacent to the northern wall and stretches approximately 4 feet into the exterior yard space.  We exposed the eastern edge of the pit, but it continues an undetermined extent beyond our excavation area to the west.  The close proximity of the pit to the greenhouse wall, combined with its size, shape, and low artifact content suggest it may have been used for enriching soils for specialized planting activities in and around the greenhouse.   The fact that the pit is located on the north side is meaningful because it indicates how the landscape may have been divided into different types of spaces.

Cassandra, Julia, and Sean peeling away the demolition debris on top of the southern wall of the greenhouse. Close up of the top of the northern greenhouse wall after the thick rubble layer has been removed (facing east)

Last Friday, we opened a second trench measuring 2×8 meters perpendicular to the first excavation area in an attempt to expose the east wall.  We have been working simultaneously in both trenches.  The surface gravel layer in the second trench transitioned rather quickly to a number of different soil deposits as well as a perplexing arrangement of mortared bricks and rocks running diagonally north-south through the western half of the trench.  At this point, one of our primary questions is whether or not this course of brick in fact represents the east wall of the greenhouse.  Or is it a more modern feature considering how close to the surface it is?  So far, the artifacts are consistent with the types found inside the greenhouse, and a possible builder’s trench characterized by a dark brown strip of soil on both sides of the mortared brick suggest it was intentionally positioned in this area, but we shall see.  Other questions concern the exterior spaces of the greenhouse identified in the northernmost and southernmost units of the first trench. 

Top of a substantial loose and set-in brick feature less than 5cm below the surface (facing north). Possibly the eastern wall of the greenhouse

Finally, in the grand tradition of saving the best for last, today Nadia and Phil were working the unit adjacent to the mortared brick feature and discovered the base of a tumbler with not only a diagnostic pontil scar, but evidence of bifacial chipping!  This tells us that once the tumbler was no longer needed to drink from, it was repurposed into a cutting or scraping tool. 

Base of a tumbler with pontil scar on the bottom and evidence of bifacial chipping along the broken edge! What sorts of things could it have been used for in a greenhouse context and who was using it?

Stay tuned for more exciting discoveries in the coming weeks!


June 11, 2012
by Fiske Center
1 Comment

New excavation areas!

It’s been a while since we updated everyone on our progress at Gore Place, so a few posts are coming soon. This one is just photographs of our original 2 by 10 meter trench and a new 2 by 8 meter trench to give people an idea of how far we have come. A post of the details of what we are finding will follow soon — I can just say that the site has some great architectural remains.

Our first trench was designed to cut across the greenhouse building; the second one should run along the south wall to hopefully find the east end.

This is how the original excavation area looked on June 6th.

This is an overview of our two excavation areas on June 11th; the first trench is in the foreground. You can see how much deeper it is than in the photo on the 6th. The new trench, which we started on Friday, is in the background.

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