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Eastern Hemlock

Latin name:
Tsuga canadensis

Extracted from a waterfront pier near Wilmington, Delaware, the tree used to make this portion of the pier
actually came from a forest located in central Pennsylvania. The outermost tree ring dates to the late 1830s.

Giant Sequoia

Latin name:
Sequoiadendron giganteum

A close up of numerous fire scars on a giant sequoia cross section from Sequoia National Park in California, dating back well prior to A.D. 1000. Look closely! Can you find the sad bearded face cradled by his hands, as if he was crying?

Douglas-fir

Latin name:
Pseudotsuga menziesii

This photo shows the tree rings from a beam extracted many years ago from a pueblo in northeastern Arizona. The section shows many false rings and many micro-rings, suggesting this tree may have been growing in a marginal environment.

Ponderosa Pine

Latin name:
Pinus ponderosa

Close up of tree rings of a ponderosa pine collected at El Malpais National Monument in New Mexico, USA, showing tree rings centered around A.D. 1400. Notice the variability in ring widths indicative of sensitivity to year-to-year variation in precipitation.

Douglas-fir

Latin name:
Pseudotsuga menziesii

Perhaps my most requested image of tree rings, obtained from a small Douglas-fir growing in the Zuni Mountains of west-central New Mexico by my colleagues Rex Adams and Chris Baisan. Not very old, but has some of the most beautiful rings of all my displays!

White Oak

Latin name:
Quercus alba

Oak cores from the Hoskins House in Greensboro, North Carolina, site of a famous battle during the Revolutionary War. The house was built from trees cut in 1811 to 1813, not cut and built in the 1780s as the historical agency had hoped.

Ponderosa Pine

Latin name:
Pinus ponderosa

This ponderosa pine once grew at El Morro National Monument in New Mexico, USA, and was cut many years ago. Once you get up close to the stump, you can see a very old scar from a fire many hundreds of years ago that scarred the tree when it only about 12 years old!

Bahamian Pine

Latin name:
Pinus caribaea var. bahamensis

We collected many cross sections of Bahamian pines that had been cut for an industrial park on the island of Abaco, but the rings are very difficult to date! Many false rings, and the pine appears to terminate tree growth during the dry season.

Longleaf Pine

Latin name:
Pinus palustris

This cross section was one of many that came from an old crib dam across a creek that was exposed after a modern dam broke in Hope Mills, North Carolina in 2003. Such sections from old-growth longleaf pines are very rare and provide information on climate back to AD 1500!

White Oak

Latin name:
Quercus alba

Sometimes you don't have to look far to find beauty in wood, and sometimes it may not be a living tree! After an oak tree was cut a year or two before this section was obtained, decay fungi had already set in, beginning to break the wood down to its basic elements.

Southwestern White Pine

Latin name:
Pinus strobiformis

I collected this fire-scarred pine on Mt. Graham in southern Arizona in fall 1991, and it remains one of the best examples of how we can determine the season of fire by looking at the position of the scar within the ring.

Bristlecone Pine

Latin name:
Pinus longaeva

Bristlecone pines have become one of the best proxy records for those who study the history of volcanic eruptions because the cool temperatures caused by these eruptions create "frost rings" that form when the cells implode from the cold.

Eastern Redcedar

Latin name:
Juniperus virginiana

Many well-preserved eastern redcedar sections have been recovered from prehistoric sites in eastern Tennessee, and they have more than enough rings to date, but we don't have a long enough living-tree reference chronology to overlap with them!

Red Oak

Latin name:
Quercus rubra

Oak is by far the most common genus we find in the many historic structures we date using tree rings in the Southeastern U.S. The genus has good ring variability and rarely has problem rings. This section came from a historic tavern in Lexington, Virginia.

Sugar Maple

Latin name:
Acer saccharum

Maple, birch, beech, and basswood are all examples of hardwood species that form diffuse porous wood, meaning that the ring contains many small-diameter vessels all through the ring. Identifying the ring boundary on this wood type is a challenge to tree-ring scientists.

Live Oak

Latin name:
Quercus virginiana

Live oak is an example of an evergreen oak, which is not common within this genus. As such, the wood is semi-ring porous and the rings are very difficult to see and date. Ring growth is also very erratic, not forming the concentric around the tree that we require.

Douglas-fir

Latin name:
Pseudotsuga menziesii

These cores were collected on Mt. Graham in southern Arizona and show a major suppression event beginning in 1685 when missing rings became evident, followed by many micro-rings. This suppression was caused by a major wildfire in 1685!

Ponderosa Pine

Latin name:
Pinus ponderosa

I find it amazing what trees can record in their tree rings! Here we see a cross section of a pine that was damaged by a major flood in the year 1945 in the Chiricahua Mountains of southern Arizona. Notice the reaction wood that formed afterward.

Pignut Hickory

Latin name:
Carya glabra

Sometimes gray-scale imagery helps define tree rings when measuring. Although classified as "ring porous" species, the rather ill-defined tree rings in hickory tree species form large earlywood vessels and smaller latewoood vessels.

Subalpine Fir

Latin name:
Abies lasiocarpa

Decay has set in on the tree rings of this dead and downed subalpine fir that once grew on Apex Mountain in British Columbia, Canada, but the tree rings can still be measured and crossdated despite this!

White Fir

Latin name:
Abies concolor

We found a beautiful fire scar on this white fir that was used to build a cabin in the Valles Caldera of New Mexico. Thought to have been built in the early 1900s, we instead found the cabin was built form white fir and Douglas-fir trees cut in 1941.

Overcup Oak

Latin name:
Quercus lyrata

These oak cores were collected in northeastern Arkansas to investigate a change in the hydrologic regime of a wildlife refuge beginning in the 1990s. We found that trees at this site experienced a major disturbance event in the 1960s.

Western Juniper

Latin name:
Juniperus occidentalis

Near Frederick Butte in central Oregon, we discovered an unusual stand of western junipers that had the most unusual lobate growth forms we had ever seen. This site yielded a drought-sensitive chronology dating back to the AD 800s!

West Indies Pine

Latin name:
Pinus occidentalis

Above 3000 meters on the highest peak in the Carribean, we found an entire forest of these pines, many with fire scars, living on a steep rocky slope. The forest looked more like the dry ponderosa pine forests of the western U.S.

Whitebark Pine

Latin name:
Pinus albicaulis

Whitebark pines growing in the northern Rockies of the western U.S. can grow to be over 1,000 years old, but the species is slowly being decimated by the introduced white pine blister rust. Many of these ancient trees are now dead with ghostly white trunks.

Shagbark Hickory

Latin name:
Carya ovata

Curiously, tree-ring scientists rarely analyze some of the more common hardwood species in the eastern U.S., such as this hickory, perhaps because such forest interior trees may contain a weak climate signal necessary for crossdating.

Virginia Pine

Latin name:
Pinus virginiana

Blue stain found in many sections of dead pines (both in the western and eastern U.S.) is caused by a fungus carried by a pine beetle. The fungus spreads into the phloem and sapwood of living and dead pines, sometimes creating stunning patterns!

Pinyon Pine

Latin name:
Pinus edulis

Burned sections of pinyon pine are commonly found in archaeological sites in the southwestern U.S. These sections can be carefully broken or surfaced with a razor to reveal the ring structure inside to assist in dating the years of construction of the site.

Red Spruce

Latin name:
Picea rubens

Conifers in the highest elevations of the Appalachians of the eastern U.S., such as this red spruce, don't experience wildfires very often, but when fires do occur, they can create numerous fire scars even in this fire-intolerant species. Notice the growth release!

White Spruce

Latin name:
Picea glauca

This tree was located in the Canadian Rockies on the toe slope of an active avalanche path. The scar was created by a debris flow or snow avalanche which struck the tree, killing a section of the living tissue. The avalanche can therefore be dated to its exact year!

Engelmann Spruce

Latin name:
Picea engelmannii

I worked considerably in the spruce-fir forests of southern Arizona in my earliest years in dendrochronology, and learned that trees with limited sensitivity can provide a vast amount of information on the history of these forests.

Ponderosa Pine

Latin name:
Pinus ponderosa

The lava flows of El Malpais National Monument in New Mexico contain vast amounts of remnant wood, mostly ponderosa pines such as this sample, and the tree rings on these samples go back nearly 2000 years! Notice the year AD 1400 on this section.

Chestnut Oak

Latin name:
Quercus montana

In the southeastern U.S., hardwood species are often scarred by wildfire. Most often, this also will cause considerable decay in the sample, but this oak had several well preserved fire scars, suggesting fire was common in these drier, lower elevation sites.

Ponderosa Pine

Latin name:
Pinus ponderosa

I originally sampled this stump in 1991 for its fire scars, located in El Malpais National Monument of New Mexico. I found it again 20 years later and was happy you could still see the tree rings and fire scars clearly! It had originally been logged in the 1930s!

Lodgepole Pine

Latin name:
Pinus contorta

This pine is found at higher elevations in the Rocky Mountains of the western U.S. At this site in Montana, we had thought we found fire scars on these pines, but it turns out that these are scars caused by bark beetles stripping away portions of the bark.

Douglas-fir

Latin name:
Pseudotsuga menziesii

These cores illustrate the level of sensitivity to climate fluctuations in Douglas-fir trees growing in El Malpais National Monument in New Mexico. These rings show the common pattern of narrow marker rings between 1800 (on the left) and 1860 (on the right).

Douglas-fir

Latin name:
Pseudotsuga menziesii

This photo shows a close-up of the rings in the previous image. The very wide tree ring is the year 1816, the "Year Without a Summer." Cooler temperatures meant more soil water for the malpais Douglas-firs, causing a wide ring for that year!

Ponderosa Pine

Latin name:
Pinus ponderosa

Dating fire scars found in the annual rings is a major application of tree-ring dating. This photo shows two scars. Notice the wider rings that formed after the upper scar, perhaps caused by removal of competing vegetation or added nutrients.

Longleaf Pine

Latin name:
Pinus palustris

Longleaf pines have the greatest ages of all the eastern pines. They grow slowly in sandy soils of the Atlantic Coastal Plain, and have proven ideal for learning about past climate and disturbance events, if old-growth stands can be located!

Rocky Mountain Juniper

Latin name:
Juniperus scopulorum

The juniper species of the western U.S. have proven a challenge in tree-ring dating, but Rocky Mountain juniper has tree rings that are easily identified and can be crossdated. Just watch out for false rings and expanded latewood!

Douglas-fir

Latin name:
Pseudotsuga menziesii

A close-up photo of tree rings in Douglas-fir reveals the individual wood cells that make up the xylem. These are called "tracheids." Notice the change in cell wall thickness from the earlywood cells to the latewood cells along a radial file of cells.

Douglas-fir

Latin name:
Pseudotsuga menziesii

The best trees for learning about past climate will be those that grow to great ages and are particularly sensitive to year to year changes in climate. This Douglas-fir began growing around the year 200 BC and lived for nearly 1000 years!

Mesquite

Latin name:
Prosopis glandulosa

Some desert species from the mid-latitudes do form annual rings, but these diffuse-porous species have rings that are difficult to see. You can use black marker and white chalk dust to help bring out the rings! The dust fills the small vessels and the rings appear!

Norway Spruce

Latin name:
Picea abies

Spruce is the preferred genus for making high-quality wooden bodies on musical instruments. This photo shows the tree rings on the outer edge of the "Messiah" violin. Analysis of its tree rings helped show that the violin was contemporary with Stradivari!

Black Locust

Latin name:
Robinia pseudoacacia

In the eastern U.S., this common hardwood species has beautiful tree rings that demonstrate the ring porous wood type. The tree species, however, has some of the densest wood found in North America and is extremely difficult to core!

White Oak

Latin name:
Quercus alba

Oak is a major genus used to build log structures in the eastern U.S. Sometimes, however, we find that the individual trees experienced some major disturbances that caused very aberrant rings, making crossdating all but impossible.

Palo Verde

Latin name:
Parkinsonia florida

A common tree species in the American Southwest, palo verde is a diffuse porous species that forms very indistinct tree rings. As a result, little tree-ring research has been performed on this genus. Best to use complete cross sections, when available.

Ponderosa Pine

Latin name:
Pinus ponderosa

A major application of tree-ring research is learning about insect populations. For example, pandora moth defoliated the needles on this tree, causing some narrow rings to be produced. We can use this pattern to learn about insect populations over many centuries!

Table Mountain Pine

Latin name:
Pinus pungens

The analysis of fire scars in tree rings can also be applied to pine species growing in the eastern U.S. Table Mountain pine has proven to be the best species in the Appalachian Mountains for learning about past wildfires!

Subalpine Fir

Latin name:
Abies lasiocarpa

Subalpine fir grows in the highest elevations of the southern Rocky Mountains and forms fairly compacent ring series. Sometime between 1979 and 1980, this tree was stripped almost completely of its bark by a black bear, but it still survived in one small area!

Florida Torreya

Latin name:
Torreya taxifolia

Perhaps the rarest conifer in the U.S., this species is on the brink of extinction because its habitat is facing mounting pressure from rapid changes in its native environment. It forms very nice tree rings, but few adult individuals are left to analyze.

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Sampling Historic Structures

Tree Ring Gallery 1
Tree Ring Gallery 2
Spectacular Trees
Beautiful Landscapes
Taking Samples
Historic Structures
Bristlecone Pines
   

The Harding Cabin at Belle Meade Plantation, reportedly built around 1807.  The Harding Cabin at Belle Meade Plantation, reportedly built around 1807, is a double-pen construction with central dogtrot, curiously built from American elm (Ulmus americana) logs (photo © H.D. Grissino-Mayer). 
Lauren Stachowiak coring a log on the Harding Cabin.  Graduate student Lauren Stachowiak cores a log on the Harding Cabin at the horsebreeding grounds of the Belle Meade Plantation, just outside Nashville, Tennessee (photo © H.D. Grissino-Mayer). 
The end of a log on the Harding Cabin at Belle Meade Plantation, Tennessee.  Looking at the end of the logs on the Harding Cabin at Belle Meade Plantation, Tennessee, we could not figure out the species. Turns out this cabin was made from American elm (Ulmus americana), a first for us (photo © H.D. Grissino-Mayer).
The Bledsoe Cabin, Wynnewood State Historic Site, Tennessee.  The Bledsoe Cabin, located at the Wynnewood State Historic Site in Castalian Springs, Tennessee, was only the second cabin we had ever encountered built fron eastern red cedar (Juniperus virginiana) trees (photo © H.D. Grissino-Mayer).
Graduate student Alex Dye drills into an eastern red cedar log on the Bledsoe Cabin.  Graduate student Alex Dye drills into an eastern red cedar (Juniperus virginiana) log on the Bledsoe Cabin, located at the Wynnewood State Historic Site near Castalian Springs, Tennessee (photo © H.D. Grissino-Mayer). 
Alex Dye pulls out an excellent core from the Bledsoe Cabin.  Alex completes the process by extracting an excellent core from the Bledsoe Cabin (photo © H.D. Grissino-Mayer).
A core that has had its outer surface darkened with a Sharpie.  To ensure we retain the outermost tree ring when we drill into a log on a historic structure, we'll blacken the surface with a Sharpie. This was taken from the Spencer Cabin at the Wynnewood State Historic Site, Castalian Springs, Tennessee (photo © H.D. Grissino-Mayer).
The Samuel Harned Cabin in Norris, Tennessee.  The Samuel Harned Cabin in Norris, Tennessee, which we sampled in July 2013. This was the first historic structure we found to be built from eastern hemlock (Tsuga canadensis) (photo © H.D. Grissino-Mayer).
Maegen Rochner sampling an eastern hemlock log on the Samuel Harned cabin in Norris, Tennessee. Graduate student Maegen Rochner displaying excellent form as she samples an eastern hemlock (Tsuga canadensis) log on the Samuel Harned cabin in Norris, Tennessee (photo © H.D. Grissino-Mayer). 

Alfred's Cabin at The Hermitage, Home of President Andrew Jackson, just outside Nashville, Tennessee

Alfred's Cabin at The Hermitage, Home of President Andrew Jackson, just outside Nashville, Tennessee. Our goal here was to determine if the double-pen saddle-bag cabin was built while Uncle Alfred was a freedman or a slave on the President's plantation (photo © H.D. Grissino-Mayer).

Extracting cores from logs in Alfred's Cabin, Nashville, Tennessee

Graduate student Tim Green (right) and Henri Grissino-Mayer extract cores from the logs that make up Alfred's Cabin using a 0.5" variable speed power drill and a specialized hollow drill bit (photo © G.G. DeWeese).

Pulling a core from an eastern red cedar log at Alfred's Cabin

Graduate student Jessica Slayton of the Laboratory of Tree-Ring Science (University of Tennessee) pulls a core from an eastern red cedar (Juniperus virginiana) log at Alfred's Cabin (photo © H.D. Grissino-Mayer). We were surprised that this entire cabin was made from eastern red cedar.

Square-shaped vat used to make saltpeter in the middle 1800s in central Tennessee

Henri Grissino-Mayer poses with a square-shaped vat used to make saltpeter a key ingredient of gunpowder (photo © D.F. Mann). Our goal was to determine when the several vats in Cagle Saltpeter Cave in middle Tennessee were constructed.

Sampling oak planks used to make saltpeter vats, central Tennessee

Henri Grissino-Mayer and graduate student Annie Blankenship (this was her M.S. project) sample oak timbers used to construct the vats (photo © D.F. Mann). We determined that one vat was constructed during the War of 1812 while the other three were constructed during or just before the Civil War.

The Devault Cabin in northeastern Tennessee, dating to the early 1800s

The Devault Cabin, just north of Johnson City, Tennessee was our very first dendroarchaeological project begun back in 2001 (photo © H.D. Grissino-Mayer). This cabin was likely an out-building, perhaps a large corn crib.

Sampling a log in the Devault Cabin

Dan MacDonald (bottom) and Henri Grissino-Mayer sampling a log on the Devault Cabin (photo © D.F. Mann). Notice how we use an extractor from an increment borer to help us line up the drill to ensure we pull a core as near to the pith as possible, thus ensuring the maximum amount of rings is obtained.

An exposed crib dam of longleaf pine logs, Hope Mills, North Carolina

A crib dam in Hope Mills, North Carolina, exposed after a modern dam broke in 2003 and released the impounded lake (photo © H.D. Grissino-Mayer). Until this project, I had never heard of a crib dam! These were built until the 19th century over creeks as a simple log structure, then covered with earth.

Henri Grissino-Mayer cutting a section off one of the rare longleaf pine logs, assisted by Justin Hart (right) (photo © S.L. van de Gevel). This crib dam was very unstable and later was destroyed by flooding. We were lucky to pull the sections from this dam before that happened.

An exposed crib dam of longleaf pine logs, Hope Mills, North Carolina

We worked feverishly for two days to cut these sections, which eventually allowed us to prove this dam was built in 1838 (photo © S.L. van de Gevel). We also used the tree rings to conduct a climate analysis.

Joseph Hoskins House in Greensboro, North Carolina

The Joseph Hoskins House in Greensboro, North Carolina, supposed built about 1780 during the Revolutionary War (photo © J.P. Henderson). Our goal was to prove if this cabin indeed was built then and likely witnessed the famous battle of Guilford County Courthouse in 1781, adjacent to the cabin.

Sampling the Joseph Hoskins House in Greensboro, North Carolina

Graduate student Joe Henderson extracts a core from one of the oak logs in the Hoskins House (photo © H.D. Grissino-Mayer). Covered with clapboard on the outside, the cabin's logs were exposed on the inside.

Extracting a core from the Joseph Hoskins House in Greensboro, North Carolina

Graduate student Joe Henderson extracts the core from one of the oak logs in the Hoskins House (photo © H.D. Grissino-Mayer). The log structure was found to be built by trees cut between 1811 and 1813, and therefore was not a Revolutionary War era cabin.

The John Ross House in Rossville, Georgia

The John Ross House in Rossville, Georgia, reportedly built by Chief John Ross of the Cherokee tribe in the late 1790s (photo © H.D. Grissino-Mayer). Our goal was to determine the harvest dates of the logs used to construct this double-pen dogtrot cabin, in collaboration with former student and lead investigator Dr. Georgina DeWeese of the University of West Georgia.

Coring logs in the John Ross House in Rossville, Georgia

Dr. Georgina DeWeese (right) and her students extract cores from the John Ross House (photo © H.D. Grissino-Mayer). Notice how one student holds the extractor to help guide the person drilling to reach the pith of the log.

Pulling a core from the John Ross House in Rossville, Georgia

Graduate student Matthew Boehm pulls a beautiful oak core from one of the logs in the John Ross House (photo © H.D. Grissino-Mayer). We found the house was instead constructed from trees cut in the period 1816 to 1819.

Governor John Sevier Cabin at the Marble Springs Historic Site in Knox County, Tennessee

The Governor John Sevier Cabin at the Marble Springs Historic Site in Knox County, Tennessee (photo © H.D. Grissino-Mayer). Sevier was a hero during the Revolutionary War and the first elected governor of the state, but did he build this cabin in the late 1790s or early 1800s?

Sampling the Governor John Sevier Cabin at the Marble Springs Historic Site in Knox County, Tennessee

Graduate students Brian Watson (right) and Chris Underwood coring the John Sevier Cabin (photo © H.D. Grissino-Mayer). The cabin had a dogtrot separating the main cabin from the kitchen.

Graduate student Saskia van de Gevel assists while fellow graduate student Chris Underwood cores (photo © H.D. Grissino-Mayer). The cabin was constructed mainly from oak logs but also had a fair amount of pine logs, which suggested to us a later construction date.

Extracting a core from the Governor John Sevier Cabin at the Marble Springs Historic Site in Knox County, Tennessee

Extracting a valuable oak core from the Sevier Cabin (photo © H.D. Grissino-Mayer). Turns out the cabin was built from trees cut in the early 1830s and could not have been built by Governor Sevier, who died in 1815.

President Abraham Lincoln Birthplace Log Cabin in Hodgenville, Kentucky

One of our most publicized projects, dating the President Abraham Lincoln Birthplace Log Cabin in Hodgenville, Kentucky (photo © H.D. Grissino-Mayer). The cabin was not what we expected, as Lincoln's father Thomas Lincoln was a skilled wood worker.

Sampling the President Abraham Lincoln Birthplace Log Cabin in Hodgenville, Kentucky

Graduate student Alison Miller cores the interior of the Lincoln Cabin (photo © H.D. Grissino-Mayer) while a film crew from the History Channel records the coring procedures. Look for "Lincoln: Man or Myth" on the History Channel.

Taking notes about the President Abraham Lincoln Birthplace Log Cabin in Hodgenville, Kentucky

Graduate students Saskia van de Gevel (top) and Georgina DeWeese count rings on the ends of logs in the Abraham Lincoln Cabin (photo © H.D. Grissino-Mayer). The trees were too young to have been cut in the early 1800s. Instead, the trees were cut in the 1840s and 1850s, so Lincoln was not born here.

President Abraham Lincoln's Boyhood Cabin just north of Hodgenville, Kentucky

This is President Abraham Lincoln's Boyhood Cabin just north of Hodgenville, Kentucky (photo © H.D. Grissino-Mayer). This cabin is much more authentic, built with very large tulip poplar and oak logs.

Counting the rings in President Abraham Lincoln's Boyhood Cabin just north of Hodgenville, Kentucky

Graduate student Chris Underwood counting rings on Lincoln's boyhood cabin (photo © H.D. Grissino-Mayer). Some of these oak and tulip poplar logs contained nearly 200 rings and the cabin is more something like Lincoln's father would have built.

Poplar Forest Plantation of President Thomas Jefferson, outside Lynchburg, Virginia

The little-known Poplar Forest Plantation of President Thomas Jefferson, outside Lynchburg, Virginia (photo © H.D. Grissino-Mayer). Our goal here was to analyze the boxwoods in the carriage circle (front center) to determine their age and substantiate whether they could have been planted by the President.

Cutting small sections from shrubs at the Poplar Forest Plantation of President Thomas Jefferson, Lynchburg, Virginia

Cutting one of the second generation dead boxwood stumps in the carriage circle (photo © H.D. Grissino-Mayer). The combined ages of the two generations indicate they date back to the period of President Thomas Jefferson.

The William Cobb House at the Rocky Mount Historic Site north of Johnson City

By far, our most controversial project on historic structures, the William Cobb House at the Rocky Mount Historic Site north of Johnson City, Tennessee (photo © H.D. Grissino-Mayer). But was this complex of cabins built in 1770, making these the earliest intact structures in the state?

Sampling the William Cobb House at the Rocky Mount Historic Site north of Johnson City

We extracted 88 cores from 65 logs from the main house and the adjacent kitchen (photo © S.L. van de Gevel). This elaborate two-story structure is not something likely to be built in 1770. We had suspicions...

Sampling the William Cobb House at the Rocky Mount Historic Site north of Johnson City

Graduate student Georgina DeWeese (left) and undergraduate Ashley Heaton extracting cores from the kitchen (photo © H.D. Grissino-Mayer). Both structures had been previously re-modeled, complicating our interpretations.

Sampling the William Cobb House at the Rocky Mount Historic Site north of Johnson City

Graduate student Saskia van de Gevel extracts a core from the north side of the main house (photo © H.D. Grissino-Mayer). The structure had architectural details that only emerged in the early 1800s.

Extracting a core from the William Cobb House at the Rocky Mount Historic Site north of Johnson City

Henri Grissino-Mayer pulls one of the longest cores ever extracted, fully 10 inches long from the Cobb House (photo © S.L. van de Gevel). The logs used were quite large, but not that old, surprisingly, averaging about 80 years in age.

Section from an oak stump underneath the William Cobb House at the Rocky Mount Historic Site north of Johnson City

The nail in the coffin. Graduate student Saskia van de Gevel and Henri Grissino-Mayer pose with a stump cut from underneath the Cobb House, which was cut in spring of 1826 (photo © L.B. LaForest). Therefore, the house could not have been built in 1770 where a tree was growing.

Stewart Carroll Cabin near Fall Creek Falls State Park in van Buren County, central Tennessee

The Stewart Carroll Cabin near Fall Creek Falls State Park in van Buren County, central Tennessee (photo © H.D. Grissino-Mayer). Made of very large tulip poplar logs, the cabin was believed to date to the 1820s or 1830s.

Taking a core from the Stewart Carroll Cabin near Fall Creek Falls State Park in van Buren County, central Tennessee

Success. The Stewart Carroll Cabin did indeed date to 1826 as was suspected (photo © S.L. van de Gevel). This was our first attempt at dating tulip poplar, a diffuse porous wood type with indistinct rings.

Double pen corn crib at the Taylor-Haynes Historic Site in Johnson City, Tennessee

The double pen corn crib at the Taylor-Haynes Historic Site in Johnson City, Tennessee (photo © H.D. Grissino-Mayer). Unknown when this was built, but the main house next door was likely built in the 1780s.

Coring the double pen corn crib at the Taylor-Haynes Historic Site in Johnson City, Tennessee

Henri Grissino-Mayer demonstrates coring a tulip poplar log in the corn crib at the Taylor-Haynes site (photo © G.L. Harley). Graduate student Lisa LaForest assists by holding an extractor to help align the drill bit.

Coring the double pen corn crib at the Taylor-Haynes Historic Site in Johnson City, Tennessee

Graduate student Nancy Li cores a log in the corn crib at the Taylor-Haynes Historic site (photo © H.D. Grissino-Mayer). The drilling process requires constant upward pressure which is difficult to maintain.

Mounted cores from the double pen corn crib at the Taylor-Haynes Historic Site in Johnson City, Tennessee

A core taken from a log in the double pen corn crib at the Taylor-Haynes Historic Site in Johnson City, Tennessee, glued and ready to be fastened with masking tape (photo © H.D. Grissino-Mayer).

The Walker Springs Cabin at the Marble Springs Historic Site in Knox County, Tennessee

Perhaps the most impressive structure we've ever worked on, the Walker Springs Cabin at the Marble Springs Historic Site in Knox County, Tennessee (photo © H.D. Grissino-Mayer). Made from very large and very old oak logs, this structure was believed to have been built in the 1820s.

Extracting a core from the Walker Springs Cabin at the Marble Springs Historic Site in Knox County, Tennessee

Graduate student Georgina DeWeese extracts a core from the Walker Springs Cabin (photo © H.D. Grissino-Mayer). Drilling at or above eye level requires eye protection.

Extracting a core from the Walker Springs Cabin at the Marble Springs Historic Site in Knox County, Tennessee

Graduate student Saskia van de Gevel extracts a core from the Walker Springs Cabin (photo © H.D. Grissino-Mayer). Notice how large the logs are, some of te largest we had ever worked on.

Pulling a core from the Walker Springs Cabin at the Marble Springs Historic Site in Knox County, Tennessee

Henri Grissino-Mayer pulls a core from the Walker Springs Cabin (photo © S.L. van de Gevel). We found out the house was indeed built from logs cut between 1826 and 1828, just as architectural historians had suggested.

The Ximenez-Fatio House in St. Augustine, Florida

Our southernmost dating project, the Ximenez-Fatio House in St. Augustine, Florida (photo © H.D. Grissino-Mayer). Was this house built in the late 1790s as historians reported, and when was the two-story structure to the right added?

Drilling a beam in the Ximenez-Fatio House in St. Augustine, Florida

Leda Kobziar of the University of Florida coring a door lintel in the Ximenez-Fatio House in St. Augustine, Florida (photo © H.D. Grissino-Mayer). The wooden portions of the house had been exposed during renovations by an architectural firm.

Mounting cores from beams taken from the Ximenez-Fatio House in St. Augustine, Florida

Leda Kobziar of the University of Florida mounts cores taken from the Ximenez-Fatio House in St. Augustine, Florida (photo © H.D. Grissino-Mayer). This is a critical process that can ruin a core if improperly mounted.

Pulling a core from the Ximenez-Fatio House in St. Augustine, Florida

Henri Grissino-Mayer of the University of Tennessee pulling a core from underneath the stairwell in the Ximenez-Fatio House in St. Augustine, Florida (photo © L.B. Kobziar). The house was indeed built in the 1790s and the wing was added in the 1850s, not the 1830s as once believed.

Sampling the double pen cantilever barn on the McDonald Farm, north of Blacksburg, Virginia  At the 2011 North American Dendroecological Fieldweek, our group sampled four structures on the Anderson-Doosing (McDonald) Farm, north of Blacksburg, Virginia. This barn had numerous logs that were all cut in the two-year period 1830 to 1831.
The salt barn at the Valles Caldera National Preserve, New Mexico At the 2012 North American Dendroecological Fieldweek, our group sampled this salt barn at the Valles Caldera National Preserve in New Mexico. It was thought to be over 100 years old but was actually constructed in 1941.

Posing with an impressive tree at the Tipton-Haynes Historic Site, in Tennessee

Students learn the basic principles and techniques of dendrochronology when exposed to research that involves dating historic sites and structures. Here, my team from the Tipton-Haynes Historic Site pose with an impressive hardwood tree (photo © H.D. Grissino-Mayer).

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