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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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Gallery of Tree Rings 1

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

My most requested image. A spectacular view of a Douglas-fir cross section.

My most requested image. A spectacular view of a Douglas-fir (Pseudotsuga menziesii) cross section obtained from the Zuni Mountains of New Mexico by my friends Chris Baisan and Rex Adams (photo © H.D. Grissino-Mayer). Note how very sensitive the ring widths are of this species, despite its young age. indicating it is ideal for reconstructing climate. This picture has appeared in over 100 publications.

A row of disrupted cells in a frost ring from a bristlecone pine

This picture shows a row of disrupted cells in a tree ring from a bristlecone pine (Pinus longaeva) growing in the White Mountains of California (photo © R.K. Adams and H.D. Grissino-Mayer). This is no ordinary frost ring. This one was formed in the year 1627 B.C., and is connected with the eruption of Thera in the Mediterranean Sea.

A Table Mountain Pine showing multiple fire scars.

A Table Mountain Pine (Pinus pungens) from Kelly Mountain in the George Washington National Forest of Virginia, U.S.A., showing multiple fire scars (photo © H.D. Grissino-Mayer).

Douglas-fir tree-ring specimen from Broken Flute Cave in northeastern Arizona

The famous Douglas-fir (Pseudotsuga menziesii) tree-ring specimen from Broken Flute Cave in northeastern Arizona, with the year AD 550 marked (photo © LTRR). Note the marker rings for the years AD 536 and 543. This tree was not 1,500 years old when it died, but was dated absolutely against a nearby reference chronology for northwestern New Mexico.

Tree rings of the famous Pemberton white oak, northeastern Tennessee

This simple image shows the tree rings of the famous Pemberton white oak (Quercus alba) tree that fell down due to old age on August 2, 2002, near Bristol, Tennessee (photo © H.D. Grissino-Mayer). The tertiary limbs on this tree dated to the 1760s. Who knows what the trunk would have dated to had it not been so decayed.

Tree rings on a fire scarred giant sequoia

Beautiful swirls of tree rings on a giant sequoia (Sequoiadendron giganteum) caused by repeated low-severity fire events on the western slopes of the Sierra Nevada of California, U.S.A. (photo © H.D. Grissino-Mayer). Can you see the face?

Tree rings on a Douglas-fir collected at El Malpais National Monument in New Mexico

The "Bannister Tree," a Douglas-fir (Pseudotsuga menziesii) collected at El Malpais National Monument in New Mexico, with a continuous sequence of rings that date from 200 B.C. to A.D. 550. This was the first tree found at the site that broke the B.C. barrier (photo © H.D. Grissino-Mayer).

Curious swirls seen in tree rings on some stinking cedar trees from northwestern Florida

The curious swirls seen in tree rings on some stinking cedar trees (Torreya taxifolia) that formerly grew in Torreya State Park, Florida, near the Appalachicola River (photo © H.D. Grissino-Mayer). The entire species is facing possible extinction from as-yet unknown reasons.

ncrement cores taken from Douglas-fir trees growing on Mt. Graham in southeastern Arizona

Increment cores taken from Douglas-fir (Pseudotsuga menziesii) trees growing on Mt. Graham in southeastern Arizona (photo © H.D. Grissino-Mayer). Note the suppression in tree growth around 1685 due to a forest fire that caused damage to the trees.

Close-up of tree rings of a bristlecone pine

Here's a close-up of tree rings of a bristlecone pine (Pinus longaeva) (photo © H.D. Grissino-Mayer). Notice the very good marker ring (the narrowest ring seen towards the right of the photograph).

Tree rings in a charcoal sample of pinyon collected from southwestern New Mexico

I've had many requests to provide digital pictures of charcoal samples that show tree rings (photo © H.D. Grissino-Mayer). This one shows tree rings in a charcoal sample of pinyon (Pinus edulis) collected from southwestern New Mexico.

Tree rings on a longleaf pine section from Lake Louise in southern Georgia

An incredible set of tree rings on a longleaf pine (Pinus palustris) section from Lake Louise in southern Georgia (photo © H.D. Grissino-Mayer). Notice how tight the ring growth is here. Longleaf pines are very slow-growing and ideal for reconstructing climate in the coastal plain region of the Southeastern U.S.

Tree rings on fossil wood showing a scar of some type

A very curious section of fossil wood that I bought online (genus and species unknown). The wood appears to belong to the hardwood group, possibly a ring porous species. But notice the internal scar over which the tree rings have grown (photo © H.D. Grissino-Mayer)!

Cross section from a white spruce that was struck by a snow avalanche

A cross section from a white spruce (Picea glauca) that was struck by a snow avalanche (impact scar on the top of the picture) in the Canadian Rocky Mountains near Alberta, Canada (photo © H.D. Grissino-Mayer and R.K. Adams).

Tree rings from a subalpine fir undergoing decay

One of the coolest sections I'd ever seen. Collected at Apex Mountain, British Columbia, Canada in 2008, this subalpine fir (Abies lasiocarpa) is undergoing decay, which causes the unusual and most beautiful pattern seen in the wood (photo © H.D. Grissino-Mayer). But, notice the rings are still visible and datable!

Tree rings on a shortleaf pine collected from a historic house being renovated in Forsyth County, Georgia

Who knows what patterns you'll see in the wood? Here's a shortleaf pine (Pinus echinata) collected from a historic house being renovated in Forsyth County, Georgia, U.S.A. showing a beautiful star like pattern emanating from an internal branch node (photo © H.D. Grissino-Mayer).

Tree rings on a diffuse porous tree species, mesquite, using a black marker and chalk dust

On diffuse porous tree species, such as mesquite (Prosopis juliflora), the rings are very faint (photo © H.D. Grissino-Mayer). So, try this. Rub some chalk or talcum powder across the sanded surface and blow off the remaining dust.

Very erratic rings found on West Indies pine

Some pine species are just very hard to work with, such as the very erratic rings found on West Indies pine (Pinus occidentalis) growing at the highest elevations in the Dominican Republic, about 3,000 meters (photo © H.D. Grissino-Mayer).

Beautiful patterns caused by decay fungi on an oak section

Dr. Charles Aiken of my department brought this oak (Quercus spp.) section to me for a workshop he was hosting, and I was struck by the beautiful patterns caused by decay fungi (photo © H.D. Grissino-Mayer).

Fire scars on a ponderosa pine tree found on a kipuka in El Malpais National Monument in New Mexico

A series of fire scars on a ponderosa pine (Pinus ponderosa) tree found growing on a kipuka in El Malpais National Monument in New Mexico (photo © H.D. Grissino-Mayer). This image clearly shows how a tree can record multiple low-severity fire scars.

Section of longleaf pine came from an 1830s crib dam, Hope Mills, North Carolina

This section of longleaf pine (Pinus palustris) came from an 1830s crib dam that was exposed after a river flooded and broke the modern dam in Hope Mills, North Carolina, U.S.A. (photo © H.D. Grissino-Mayer).

Eastern red cedar that had been excavated from an archaeological site in southeastern Tennessee

A section of eastern red cedar (Juniperus virginiana) that had been excavated from an archaeological site in southeastern Tennessee in the 1930s (photo © H.D. Grissino-Mayer). It remains undated but likely dates to pre-1300. The sample shows the excellent tree rings that can be preserved in ancient wood.

Cross section of a giant sequoia showing a remarkable release in growth

A cross section of a giant sequoia (Sequoiadendron giganteum) showing a remarkable release in growth (notice the wider rings that start in the middle of the photo) following a widespread and intense fire in A.D. 1297 (photo © T.W. Swetnam and A.C. Caprio).

Close up of tree rings seen in a stinking cedar from Torreya State Park

Tree rings seen in a stinking cedar (Torreya taxifolia) from Torreya State Park in the panhandle of Florida (photo © H.D. Grissino-Mayer). They are very faint for a conifer, but still show enough variability to be crossdated!

Tree rings on a lodgepole pine collected on Morrell Mountain in the Lolo National Forest

Tree rings on a lodgepole pine (Pinus contorta) collected on Morrell Mountain in the Lolo National Forest of western Montana (photo © H.D. Grissino-Mayer). The scars were once thought to be caused by fire, but we believe these to be caused instead by bark beetles.

Tree rings on a live oak from Ft. Sumter National Monument in South Carolina

Tree rings on a live oak (Quercus virginiana) from Ft. Sumter National Monument in South Carolina, U.S.A. showing the erratic and very indistinct ring patterns associated with this evergreen oak (photo © H.D. Grissino-Mayer).

Sectio of ponderosa pine showing an impact scar from a flood in southeastern Arizona in 1945

This ponderosa pine (Pinus ponderosa) was growing alongside a stream in Pine Canyon in the Chiricahua Mountains of southeastern Arizona (photo © H.D. Grissino-Mayer). The impact scar on the right was from a flood. Notice the resin behind the scar and how the tree leaned to its left after it was struck by the flood water.

Fire scar on a red spruce collected from Mt. Rogers in the southern Appalachians in southern Virginia

This photo shows a fire scar on a red spruce (Picea rubens) collected from Mt. Rogers in the southern Appalachians in southern Virginia (photo © A. Krustchinsky). This must have been a low-intensity fire to have scarred the tree when it was so young, dispelling the myth that fires do not occur in such mesic, high-elevation locations of the eastern U.S.

Subalpine fir from Mt. Graham, southeastern Arizona, showing a scar from bear stripping

I found this subalpine fir (Abies lasiocarpa) log in a pile of logs on Mt. Graham, southeastern Arizona, in late 1990 (photo © H.D. Grissino-Mayer). The scar was caused by a bear peeling away most of the bark, yet a small portion of the tree remained living, causing this unique formation.

Tree rings from a red oak extracted from a squared beam from a historic structure in Lexington, Virginia

Tree rings from a red oak (Quercus rubra) extracted from a squared beam from a historic structure in Lexington, Virginia (photo © H.D. Grissino-Mayer). This sample helped us date when the structure was likely built.

Tree rings from a Rocky Mountain juniper, El Malpais National Monument, New Mexico

This Rocky Mountain juniper tree (Juniperus scopulorum) is the oldest tree yet found in New Mexico (photo © H.D. Grissino-Mayer). It grew in the lava fields of El Malpais National Monument for 1,889 years!

Tree rings on American basswood enhanced with digital imagery

Tree rings on American basswood (Tilia americana) are very difficult to see because it is a diffuse porous type of wood (photo © H.D. Grissino-Mayer). I tried enhancing the rings using image analysis software and got this beautiful pattern.

Close-up of tree rings from a ponderosa pine tree growing in El Malpais National Monument, New Mexico

A fairly close-up image of tree rings from a ponderosa pine tree (Pinus ponderosa) growing in El Malpais National Monument, New Mexico (photo © H.D. Grissino-Mayer).

Fire scars on an oak growing in a drainage bottom in the Jefferson National Forest, of southwestern Virginia

Fire scars can be found in oak species (Quercus spp.) growing in mesic locations in the eastern U.S. (photo © H.D. Grissino-Mayer). This tree was growing in a drainage bottom in the Jefferson National Forest, of southwestern Virginia.

unusual tree rings on a western juniper growing near Frederick Butte in central Oregon

Sometimes you find a tree so unique, it has its own story, one that lasts 700 years as did the one from this western juniper (Juniperus occidentalis) growing near Frederick Butte in central Oregon (photo © H.D. Grissino-Mayer). It had been long-dead already when we sampled it.

Close-up of a ponderosa pine tree from El Malpais National Monument, New Mexico

Close-up of CRE340, a ponderosa pine (Pinus ponderosa) tree from El Malpais National Monument, New Mexico (photo © H.D. Grissino-Mayer). Notice the pinpricks for the year AD 1400 (three dots) and for AD 1390 (one dot below). Also notice the narrow rings for the years AD 1399, 1405 and 1407, a classic "signature" pattern.

Close-up of boxwood shrub rings from President Thomas Jefferson's Poplar Forest Plantation near Lynchburg, Virginia

Close-up of boxwood (Buxus sempervirens) shrub rings, from a sample collected at President Thomas Jefferson's Poplar Forest Plantation near Lynchburg, Virginia (photo © H.D. Grissino-Mayer).

Section from eastern hemlock cut from a log used in a pier in Dover, Delaware

A section from eastern hemlock (Tsuga canadensis) cut from a log used in a pier in Dover, Delaware (photo © H.D. Grissino-Mayer). We were able to date this log as having come from central Pennsylvania.

Section from an Engelmann spruce that was logged during construction of an observatory on Mt. Graham in southeastern Arizona

A section from an Engelmann spruce (Picea engelmannii) that was logged during construction of an observatory on Mt. Graham in southeastern Arizona, U.S.A. (photo © H.D. Grissino-Mayer). Although small, the tree was quite old, having spent much of its life in the understory.

Section from a Douglas-fir that was cut from a beam located in a pueblo in northeastern Arizona

A section from a Douglas-fir (Pseudotsuga menziesii) that was cut from a beam located in a pueblo in northeastern Arizona (photo © H.D. Grissino-Mayer). The opposite side contains axe cut marks.

Close-up of tree rings from a section from a Douglas-fir that was cut from a beam located in a pueblo in northeastern Arizona

Close-up of tree rings from a section from a Douglas-fir (Pseudotsuga menziesii) that was cut from a beam located in a pueblo in northeastern Arizona (photo © H.D. Grissino-Mayer). Notice the numerous false rings and very tight narrow rings to the left.

Section from a Table Mountain pine sapling collected on Brush Mountain in southwestern Virginia

A section from a Table Mountain pine (Pinus pungens) sapling collected on Brush Mountain in southwestern Virginia in 1993 (photo © H.D. Grissino-Mayer). We were surprised to find a buried scar on such a small (5 cm diameter) sapling. The sapling was no more than 10 years old when first scarred.

Close-up of a fire scar that was dated to 1842, as captured on this southwestern white pine from Mt. Graham in southern Arizona

A close-up of a fire scar that was dated to 1842, as captured on this southwestern white pine (Pinus strobiformis) from Mt. Graham in southern Arizona (photo © H.D. Grissino-Mayer). The scar position indicates this fire occurred early in the growing season (May or June) of 1842.

Palo verde, a diffuse porous wood species commonly found in the southwestern U.S.

Palo verde (Cercidium microphyllum), a diffuse porous wood species commonly found in the southwestern U.S., has indistinct growth rings and therefore can not be dated using dendrochronology (photo © H.D. Grissino-Mayer).

Tree rings from a sugar maple, which is common throughout the eastern U.S.

Sugar maple (Acer saccharum) is common throughout the eastern U.S. (photo © H.D. Grissino-Mayer). Even though this species also contains diffuse porous wood, the tree rings can be distinguished and dated using dendrochronology.

Wood from Norway spruce is commonly used to make musical instruments

Wood from Norway spruce (Picea abies) is commonly used to make musical instruments (photo © H.D. Grissino-Mayer). In this photo, one can see the "side grain" view of tree rings running longitudinally down the trunk of tree. These can also be dated when viewed in this position.

Section from a longleaf pine that was excavated from the Fountain of Youth State Park archaeological site in St. Augustine, Florida

A cross-section from a longleaf pine (Pinus palustris) that was excavated from the Fountain of Youth State Park archaeological site in St. Augustine, Florida, U.S.A. (photo © H.D. Grissino-Mayer). The sample was dated to the mid-1600s.

Section of a longleaf pine was cut from a very eroded stump on the edge of Lake Louise in southern Georgia

This section of a longleaf pine (Pinus palustris) was cut from a very eroded stump on the edge of Lake Louise in southern Georgia, U.S.A. (photo © H.D. Grissino-Mayer). The tree rings date back to A.D. 1421!

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