Wooster’s Fossils of the Week: Geological Magic Lantern Slides from the 19th Century (Part II)

December 2nd, 2016

12-iguanodon-and-a-hyleosaurusThis is a continuation of last week’s post about a set of 19th century “Magic Lantern Slides” found in Scovel Hall at Wooster. These evocative scenes are taken from reconstructions of ancient life by Benjamin Waterhouse Hawkins (1807-1894). In 1855, Waterhouse Hawkins finished sculpting life-sized models of these extinct animals, along with many others, for the Crystal Palace gardens in London. Most of these extraordinary animal statues still exist.

Above is the Waterhouse Hawkins version of the Early Cretaceous dinosaurs Iguanodon (the critter on top) and Hylaeosaurus (the two on the lower level). These two genera, along with Megalosaurus, were used as the basis for the new Dinosauria erected by Sir Richard Owen in 1842, a mere dozen years before these models were created. Both of these dinosaurs were herbivorous, Iguanodon being an ornithopod and Hylaeosaurus a basal ankylosaur. They are said here to be from “the Secondary Epoch of the Earth’s history”.

13-an-iguanodon-and-a-hyleosaurus-by-benjamin-waterhouse-hawkins-1853A print version of the same scene. Modern reconstructions of these animals are dramatically different, of course. Waterhouse Hawkins was advised by Owen to make these versions as mammalian as possible. The stance and articulation of limbs is the largest change in our conception of these genera. The Iguanodon model is where a famous 1853 New Year’s Eve dinner party was held.

14-megatherium-glyptodonThis next slide is another Waterhouse Hawkins creation of a much later scene. These are reconstructions of the South American ground sloth Megatherium, which lived from the Pliocene through the Pleistocene. Aside from some unnecessary bulk, these reconstructions are not too far off from how we conceive the giant ground sloths today.

16-no-labelThis magic lantern slide from Wooster’s collection is unlabeled, and I’ve found no trace of the image online. The scene has a Mesozoic vibe, with a crinoid, ammonites (or nautiloids?), and a lurking reptile. Any identifying information would be appreciated!

17-anoplotherium-gracile-palaeotheriumAnother Waterhouse Hawkins theme, this time of Eocene ungulates. The label says they are Paleotherium (in the right foreground) and Anoplotherium gracile (on the left in the foreground). Both were originally described from the Paris region by the magnificent Georges Cuvier.

9-benjamin_waterhouse_hawkins-_photograph_by_maull__polyblankBenjamin Waterhouse Hawkins (1807-1894) was a Londoner skilled in natural history and art. His lifetime honors are a clue to his abilities: He was a Member of the Society of Arts, a Fellow of the Linnean Society, and a Fellow of the Geological Society of London. His Crystal Palace dinosaurs are his best know combination of art and science, but he produced much besides. For example, he drew figures for The Zoology of the Voyage of HMS Beagle. In 1868 he mounted a skeleton of Hadrosaurus in Philadelphia, the first dinosaur to be displayed in this way. Through his art and connections in the paleontological world, Waterhouse Hawkins brought fossils to life for millions of people in Victorian times.

 

Wooster’s Fossils of the Week: Geological Magic Lantern Slides from the 19th Century (Part I)

November 25th, 2016

1-teleosaurus-ichthyosaurus-pentacrinites-ammonites-gryphaea“Wooster’s Fossil of the Week” is not always about actual fossils, but our topics are each paleontological. Many years ago I discovered in an old box tucked away in the attic of Scovel Hall at Wooster a set of “Magic Lantern Slides” used in geology courses. I came across them again recently and thought I would share these ancient scenes. Lantern slides were the 19th Century equivalent of PowerPoint, so generations of Wooster geology students must have sat in rapture looking at these colorful images. (At least that’s how I imagine them now viewing my PowerPoint slides!) The above imagined seashore view includes the crocodylian Teleosaurus atop the layered rocks, Ichthyosaurus immediately below, four long-necked Plesiosaurus on the left, an orange cluster of the crinoid Pentacrinus rooted inexplicably in the beach sand, and a scattering of ammonite and oyster shells.  The caption on the image says these animals lived during “the Secondary Epoch of the Earth’s history”. We would now say this is a Jurassic scene. The ichthyosaur looks the most odd to us. Not only is it crawling on the land, it lacks a dorsal fin and the characteristic bi-lobed, shark-like tail. These were later discoveries about ichthyosaurs made only after specimens were found with skin impressions.

2-ammonite-lantern-detailThis close-up shows the detail in these images. Ammonites are on the left (“6”) and the oyster Gryphaea is on the right (“7”).

3a-magic-lantern-slide-geological-585The Magic Lantern Slides are 4×8 inches with the image on glass fixed in a thin slab of wood with metal rings. These are chromolithograph slides, each stamped “T.H. McAllister, Optician, N.Y.”. McAllister was the most prominent of many American producers of lantern slides in the late 19th century.

4-megalosaurus-pterodactyleThe quadrupedal beasts in the foreground are the of the Jurassic theropod dinosaur Megalosaurus, with pterodactyls in the background. We now know Megalosaurus was bipedal, like all theropod dinosaurs.

5-megalosaurus-headAnother detail showing the fine quality of these color images on glass.

6-gigantic-lizards-and-some-pterosauria-by-benjamin-waterhouse-hawkins-1853Most readers with any background in the history of paleontology recognize these reconstructions of ancient life from the work of Benjamin Waterhouse Hawkins (1807-1894). In 1855, Waterhouse Hawkins finished sculpting life-sized models of these extinct animals, along with many others, for the Crystal Palace gardens in London. He was advised for the anatomical details by Sir Richard Owen (1804-1892), a hero of paleontology but not a fan of Darwinian evolution. He is responsible for the dinosaurs of Waterhouse Hawkins looking rather mammalian. Most of these extraordinary animal statues still exist.

9-benjamin_waterhouse_hawkins-_photograph_by_maull__polyblankBenjamin Waterhouse Hawkins (1807-1894). More reconstructions from him, along with his brief biography, in the next installment.

 

Wooster Geologists explore Bristol, England

June 12th, 2016

1 Temple Church interior 585Bristol, England — Cassidy Jester (’17) and I spent the day in Bristol as we await our trip to London tomorrow. We began a rainy, gray morning in the harbor region in museums and historical ships. We were turned away from the Cathedral because it was, naturally enough, Sunday morning. We did get a peek at the finery and costumes of people attending a special service for the Queen’s Pretend 90th Birthday. (Her real birthday being in April. Royals get an extra birthday of their choice, apparently.) From our diverse visits today, I want to present two short pictorials.

Above is an interior view of Temple Church in the Redcliffe district of Bristol, about a block from our hotel. The weather had much improved by the afternoon. Tim Palmer introduced me to this site last year.  This building has been in ruins since the night of November 24, 1940.

2 Temple Church 1940German bombers, during the Bristol Blitz, dropped incendiary bombs on the roof of Temple Church, starting a fire that collapsed the roof, damaged the arcades, and destroyed all the wood furnishings. The building was effectively destroyed, but the ruins were not only left standing, they were reinforced against further collapse.

3 Temple Church 1This is a view of the eastern wall showing the skeletal remains.

4 Temple Church 2The surviving tower.

5 Templar Church in Temple ChurchIn an interesting twist, after the destruction, archaeologists were able to dig into the foundations of Temple Church. The tradition was that the original church building was round. Indeed, round outlines appeared, along with column remnants of a monastery built in the early 12th century by the Order of the Knights Templar. This was a Templar Church in their traditional style evoking the Temple in Jerusalem. Only nine of these round churches were built in England.

6 Queen Square 061216Another site that impressed me was Queen Square. In the center is a statue of King William III (William of Orange, “King Billy”, and the William of “William and Mary”). The square was lively today with a refugee relief concert.

7 Queen Square 1831This is Queen Square on a hot night in 1831. The statue of King Billy has lots of company. Queen Square was the epicenter of the 1831 Bristol Riot over the rejection of a Reform Bill by the House of Lords. At that time only 6000 men of the population of 104,000 were franchised. There was great violence and much destruction that had a deep effect on the nation. The Reform Act was passed the next year.

Two brief Bristol stories!

 

Wooster Geologists in Bristol, England

June 11th, 2016

1 Bristol Museum and UniversityBristol, England — Cassidy Jester (’17) and I are spending the weekend in Bristol after finishing our fieldwork in Dorset this week. Our travel and lodging arrangements required a couple of days here before we go to London on Monday and then our separate ways. We’ll continue to sort out our specimens, work on a GSA abstract, and explore the city. This afternoon, while waiting for our hotel rooms to open, we walked through the central part of the city to the Bristol City Museum and Art Gallery. It is the building with the pillars on the left. The magnificent tall building on the right is part of the University of Bristol — the part that houses the Earth Sciences Department.

2 Bristol City Museum and Art GalleryThis museum is a wonderful combination of art, history and science, with considerable space devoted to geology and paleontology.

3 Bristol pregnant ichthyosaurAmong the many exhibits, I picked one to share: a pregnant ichthyosaur from the local Jurassic. Note the tiny arrow in the lower left of the skeleton.

4 Bristol ichthyosaur fetusAt the arrow, among the bones of this female ichthyosaur is this hand-sized skeleton of a fetus, direct evidence that ichthyosaurs, though reptiles, gave live birth. Paleontology is so cool.

Team Dorset finishes its fieldwork

June 10th, 2016

1 Snuffbox serpulidssSherborne, England — Cassidy Jester (’17), Tim Palmer and I today finished our fieldwork. Cassidy is now set for her Senior Independent Study project with plenty of specimens, observations, photographs and ideas to last the next 10 months. This morning we visited the Burton Bradstock beach exposure of the snuffboxes, meeting our great colleague Caroline Buttler (Department of Natural Sciences, Amgueddfa Cymru – National Museum Wales, Cardiff) and her husband Simon for lunch on the outcrop. It was great fun, and Caroline had additional discoveries for us, including the exfoliated snuffbox layer shown above with serpulid worm tubes.

2 Ammonite gastropod snuffboxesWe had time to look for more fossils associated with the snuffboxes. Above you see a gastropod on the left and an ammonite on the right, with snuffbox bits scattered about.

3 Burton Bradstock pendentWe also found many examples of burrow systems with cryptic pendent iron-rich layers, including those shown above. (I rotated the image 180° because the block we studied on the beach is upside-down.)

4 Maiden Castle rampartsOn the way back to our lodgings near Sherborne we stopped by the Iron Age hill fort Maiden Castle, a portion of the massive earthen ramparts of which are shown above.

Our collecting, measuring and describing is done. Most of the work for this project, of course, will be in the Wooster geology labs. We will have delightful memories of our sunny days in Dorset, and the invaluable assistance of our colleagues Bob Chandler and John Whicher. I am personally most grateful for the geological and navigational skills of Tim Palmer, our wonderful companion and astute advisor. Without him none of this could be done.

Crew in Whicher MuseumThe Dorset crew in the Whicher Museum. From the left, Bob Chandler, Mark Wilson, Tim Palmer, John Whicher, and Cassidy Jester (’17).

Team Dorset makes a cryptic discovery

June 9th, 2016

1 Cassidy Mapperton 060916Sherborne, England — It was a good day for Team Dorset. Cassidy Jester (’17) is shown above in Coombe Quarry near Mapperton, Dorset. She is standing on an erosion surface between the Comptocostosum Bed (Aalenian) below and Horn Park Ironshot (Bajocian) above. These are beds 2d and 3a in the local stratigraphic system, and ammonite zones Scissum and Discites. There is a considerable disconformity here, meaning a significant hiatus of unrecorded time, several ammonite zones worth. The snuffboxes we’re interested in are found jut above this boundary.

2 Pendent layers 060916Tim Palmer picked up the above rock as we started our measurements and descriptions. He deduced right away that he was looking at a cross-section of a burrow now filled with light brown sediment. The darker layers above are ferruginous (iron-rich), serpulid-bearing laminae like those that make up the snuffbox cortices, and they are hanging pendently from the roof of this burrow into the original cavity beneath. At one time this burrow was an open tunnel with cemented walls and the iron-rich layers grew from the ceiling like stalactites. Tim demonstrated with this single specimen that the iron-rich layers grew in dark, cryptic spaces, strongly supporting the hypothesis of Palmer and Wilson (1990) that the equivalent snuffbox layers accumulated on the undersides in gloomy darkness

3 Infilled Thalassinoides MappertonCassidy and I then recognized that the iron-rich “stromatolites” we had seen on our earlier visit to the quarry were actually these iron-rich layers filling Thalassinoides burrow systems that are truncated by the erosion surface. In the above image you are looking down on the erosion surface at a branching burrow filled with iron-rich layers. These are not stromatolites but cryptic burrow fills.

5 Sherborne Thalassinoides 2 585Later in the afternoon we returned to the Sherborne Stone quarry yard and looked at Thalassinoides burrow systems in the Sherborne Building Stone cut by giant saws. We see here a view parallel to bedding showing a box work of tunnels filled with a darker sediment. This matches the pattern seen in the Coombe Quarry erosion surface.

6 Sherborne Thalassinoides section 585This is a cross-section of the same kind of Thalassinoides burrow in the Sherborne Building Stone. We see the vertical connections to the surface and the lateral tubes. These burrows formed the cryptic spaces for iron-rich layer deposition as seen at Coombe Quarry. Or at least that is our hypothesis! Tomorrow we will test it by examining the burrow systems associated with the snuffboxes at Burton Bradstock.

7 Sherborne Castle 585As usual, we ended our day with more historical architecture and stonework, this time at nearby Sherborne Castle, a 16th century Tudor mansion sitting on magnificent estate grounds. Much of our work is on land owned by this estate.

The format below is a bit messy, but here is a download of our GPS data for the localities on this expedition:

GPS# Latitude Longitude Location
138 50.96268903 -2.503268039 Frogden Quarry
139 50.96319797 -2.501848983 Frogden Quarry older
140 50.93710503 -2.601833018 Babylon Hill
141 50.94292902 -2.556813983 Louse Hill
142 50.79496597 -2.71623401 Coombe Quarry, Mapperton
143 50.70015801 -2.734380998 Hive Beach, Burton Bradstock
145 50.81626003 -2.771674013 Horn Park
146 50.70154396 -2.737065973 Burton Bradstock snuffboxes

Snuffboxes! Team Dorset has a project

June 8th, 2016

1 Snuffbox colection BBSherborne, England — Cassidy Jester (’17) now has a Senior Independent Study project: Origin and paleoecology of ferruginous oncoids (“snuffboxes”) from the Middle Jurassic (Bajocian) of southern England and northern France. (We’re not going to France; I have specimens I collected 20 years ago there.) Pictured above is a nice collection of these snuffboxes on the Dorset coast near Burton Bradstock. More on them below. Today Tim Palmer, Cassidy and I had a great time starting our data collection.

2 Whicher museumThe first thing we did this morning, though, was visit the astounding fossil collection of John Whicher, one of our new citizen scientist friends. He has a spectacular collection of exquisite fossils, most from the Inferior Oolite and all meticulously curated. His preparations are amazing, especially when you know what a fossil looks like when first collected.

3 Tim Cassidy Whicher museumTim and Cassidy are here admiring some of the Inferior Oolite ammonites in John’s display cases. Each specimen is numbered and has full locality and stratigraphic context.

4 Whicher workshopJohn has a workshop that would be the envy of any university, along with storage for those specimens awaiting his patient preservation. Here we see our other new friend Bob Chandler cutting a rock for us. Bob has his own equal collection. These indefatigable amateurs are making extraordinary contributions to science.

5 Burton cliff fallAt noon we started our own work along the coast at Burton Bradstock, Dorset. We depended upon cliff falls like this one where the rocks of the Inferior Oolite at the top of the cliff crashed to the beach below.

6 Burton Bradstock large block 060816This gorgeous block is an example of the snuffbox bed fallen into our hands on the Burton Bradstock beach. The long part of the measuring stick is one meter. We are looking at the base of the snuffbox-bearing unit, so the block is upside-down.

7 Cassidy working 060816Cassidy is here studying that above block, with the English Channel in the background and brilliant sunlight.

8 Snuffbox bored shell nucleusThis is one of the snuffboxes with a shell fragment as a nucleus. The shell has many borings that were excavated before it started accumulating the layers of iron oxides.

9 snuffboxes horns ooidsThe snuffboxes have all sorts of details, from the compositions of the nuclei, the structure of the cortices, the fossils found encrusting them, and their overall shapes. Many have “horns” in cross-section like the two above. Note also the iron ooids (rusty red dots) between the snuffboxes. Their origin is another mystery.

10 Cerne Abbey 585We ended the day with a visit to the ruins of Cerne Abbey in Cerne Abbas, which was founded in 987. The remaining buildings are considerably later but still incorporate remnants of the old. This is now a romantic ruin on a small estate.

11 Cerne Abbey signTomorrow we continue to study the snuffboxes in other localities. We hope again to avoid the rains that have affected much of the country this week.

Reference:

Palmer, T.J. & Wilson, M.A. 1990. Growth of ferruginous oncoliths in the Bajocian (Middle Jurassic) of Europe. Terra Nova 2: 142-147.

 

 

Team Dorset arrives in England

June 5th, 2016

1 Temple Meads StationIlminster, Somerset, England — Little Team Dorset, consisting of Cassidy Jester (’17) and me, arrived today in England after a long journey of cars, planes and trains. As you can see from the above image of the Bristol Temple Meads train station, we have brilliant weather. Cassidy and I are here to do the fieldwork for her Independent Study project in the Inferior Oolite (Jurassic, Bajocian) of inland Dorset. We met Tim Palmer at the train station and then drove into Somerset for the afternoon and evening. Tim Palmer and I explored the Inferior Oolite and other units in this region last year to prepare for this expedition.

2 Hinton Blewett St MargaretIf you know anything about Tim Palmer, you know we’re going to examine building stones every chance we get. This is an ideal introduction to our project because of its combination of geology and history. Tim is a master of this topic, especially Jurassic stones. We first stopped in the little parish of Hinton Blewett to examine a Medieval baptismal font in the 13th century Church of St. Margaret (above).

3 Hinton Blewett font and TimHere is Tim examining the baptismal font, looking closely at the stonework.

4 Hinton Blewett font 585The font is made of Dundry Stone, from the top of the Inferior Oolite, with the exception of a later addition of an oolitic limestone cylinder in the stem, apparently to raise it a bit higher. The basin is lined with hammered lead.

5 St Margaret stone Hinton BlewettThe oldest stone in the structure of the church itself is also a Jurassic limestone. It shows these distinctive patterns of iron-rich layers.

6 Wells Cathedral frontWe next visited Wells and its magnificent cathedral. This is the first time I’ve been here. It is spectacular, especially in the brilliant sunlight. It is made mostly of Doulting Stone, a local limestone Tim and I studied last year.

7 Wells top detail 585The front of Wells Cathedral has dozens of Medieval statues, most still well preserved. Christ and the apostles make up the first two rows, followed by English bishops.

8 Wells detailMost of the statues are protected within stone niches.

9 Wells ClockUnusual for English cathedrals, there is a large clock with animated figures that ring bells. This is a feature more common in continental Europe.

10 Purbeck Carboniferous DoultingThis beautiful detail shows a pillar of Purbeck Marble, topped with a disk of dark Carboniferous limestone, and then the Doulting stone.

11 Vicars' Close 585We then visited the famous Vicar’s Close near Wells Cathedral, which is the oldest preserved residential street in Europe. The houses were built in the 14th and earl 15th century.

Tim, Cassidy and I then drove to Ilminster for a night in a Travelodge before fieldwork begins tomorrow. We had an excellent day.

 

A Wooster Geologist visits the caves of Tel Maresha in central Israel

March 21st, 2016

1 Bell caves MareshaTEL AVIV, ISRAEL — My last day in Israel was spent with my friend Yoav Avni exploring some sites in the central part of the country before my flight left Tel Aviv late in the evening. The most geological place we visited was Maresha (which later became, in order, Beit Guvrin, Eleutheropolis, Bethgibelin, Bayt Jibrin, Kibbutz Beit Guvrin and Beit Guvrin National Park — you know there’s a long story there!). Maresha was an 8th Century BCE Israelite city in Judah that guarded several trade routes and access to the Judean hills from the coast. It thus had significant strategic value and was subject to just about every conqueror of the region since the Iron Age. The bedrock has a very thick section of the Maresha Formation (Eocene), a homogeneous soft chalk that is easily carved. This chalk has long been quarried for building stone and the main component of plaster and cement. The typical quarries are bell-shaped, with a small circular entrance from ground level and an expanding cone downwards. Above we see several intersecting quarries exposed by a roof collapse.

2 Bell caves signHere is a helpful diagram showing the construction of bell caves. The top geological layer is a hard calcrete (caliche) locally called nari. It provides a strong roof for the quarries.

3 Bell cave openingThe opening of a bell cave through the calcrete upper layer.

4 Bell cave carving marksThe sides of the quarries easily show the tool marks made by the workers as they spiraled down into the bedrock. This rock is soft enough to dig with your fingernails.

5 Columbarium Maresha

Residents of Maresha, especially in the diverse Hellenistic times (2nd-3rd centuries BCE), reused the quarries for living and working spaces, expanding several into new rooms. Above Yoav is standing in the largest columbarium, a place to raise doves for food and rituals. (Not for the storage of ancestral ashes or bones, as was once thought.)

6 Yoav in Columbarium MareshaI didn’t want to crop out Yoav’s happy face! He is standing in the bottom of a bell cave repurposed as a columbarium.

7 Olive cracker MareshaThere are several underground olive oil factories that were active from the 3rd Century BCE until modern times. This device was driven by a donkey to crush raw olives.

8 Large olive press MareshaThis is an underground olive press. Heavy stones were attached to the beams to press the juices out of olives cracked first by the donkey apparatus above.

9 Siddonian cavesThe Sidonian tombs (about 2nd Century BCE) are very impressive. All the carving is original, but the paint shown above is a modern reconstruction. This inscription on a tomb here is haunting:

Nothing else remains that I can do for you, or that will pleasure you. I am sleeping with someone else, but it is you I love, dearest to me of all.

In the name of Aphrodite, I am happy about one thing, that your cloak has been left to me as a pledge.

But I flee, and permit you expanses of freedom. Do anything you desire.

Do not strike the wall; it only makes noise. We will motion to each other; this will be the sign between us.

10 Maresha countrysideThe scenery above ground at Tel Maresha is lush and green. This region received more than the usual amount of rain this season, and it shows. We are looking here from the tel towards Hebron in the Judean hills. Note the herd of sheep in the middle ground distance.

11 Bedouin sheep MareshaLater in the day we met those sheep and their Bedouin shepherds.

12 Tel MareshaAnd here is Tel Maresha itself. Only 10% has been excavated, so much more remains to be discovered.

__________________________

My tradition at the end of a field excursion is to include my most important GPS numbers and coordinates:

125: N29.99183°, E35.07680° Gerofit Junction Ora Formation
126: N30.94310°, E34.97972° SU62 below oolite; nice corals
127: N30.94323°, E34.99110° Top Zohar Cliff
128: N30.95774°, E35.00615° SU65 bedding plane
129: N30.94358°, E34.97828° SU65 in Matmor Hills
130: N30.94812°, E35.00099° Lowest exposed Zohar
131: N30.33491°, E34.92828° Road to Be’er Ada
132: N30.32229°, E34.90701° Be’er Ada
133: N30.32553°, E34.90683° Near Be’er Ada along fault
135: N30.32973°, E34.91417° Ada Canyon top view
136: N30.32001°, E34.97467° Wadi Paran cliffs

Wooster Geologists on the Gettysburg Battlefield

October 12th, 2015

1 Devil's Den longer viewGloria and I and our daughter Amy took advantage of the first days of Fall Break at Wooster to visit the Gettysburg Battlefield in Pennsylvania, about a 5.5 hour drive from home. The weather was spectacularly beautiful, as you can see in these images. The blue skies and bright sun made the place all the more heart-wrenching, though, considering the events of July 1-3, 1863, commemorated so vigorously here. This is one of the best maintained battlefield in the world, and one of the most visited. Over four million tourists (or, arguably, pilgrims) travel to this site in eastern Pennsylvania every year. They are greeted by more than 1200 monuments (“stone sentinels“) to this American Civil War battle. There were over 45,000 casualties on both sides, making it the bloodiest battle in North American history.

The geology of the Gettysburg battlefield is very well known, and much has been written about how the bedrock provided the dramatic setting and constrained the tactics of both sides. In a simple summary, during the Triassic break-up of the supercontinent Pangaea, rift basins occurred along what would become the northeastern margin of North America. A variety of sediments filled these widening valleys as the terrain around them eroded. The thinning crust below produced considerable igneous activity and these sediments were intruded by dikes and sills made of the igneous rock diabase. Diabase is very hard and resistant, so when this area was later eroded, the igneous bodies stood in relief from the softer materials around them, forming rocky hills and ridges. In the top image we see this diabase exposed at a place on the battlefield known as Devil’s Den. During the battle the Union forces occupied most of the high ground underlain by these diabase rocks, including iconic names like Little Round Top, Cemetery Ridge and Culp’s Hill.

I have no intent of telling the story of the Gettysburg battle here. What follows are just a few images of the places most meaningful to me.

2 Devil's Den closer viewIt is at Devil’s Den that we see the best exposures of the diabase. This place was occupied by Confederates during most of the battle, and is probably most famous for the photographs of Confederate dead. The top surfaces of these rocks are worn slick by the shoes of visitors over the past 150 years.

3 Diabase stone wall GettysburgThe hard diabase was immediately useful to Union troops, who constructed these low stone breastworks across the western slopes of Little Round Top, Cemetery Ridge and Culp’s Hill. The bedrock is very close to the surface, so it was impossible to dig useful trenches or foxholes.

4 Little Round Top 101215The focus of my pilgrimage every time I visit Gettysburg is Little Round Top, seen here from Devil’s Den looking eastward. In one of the most dramatic actions of the battle, college professor Colonel Joshua Lawrence Chamberlain led his men of the 20th Maine in a desperate bayonet charge downhill into advancing Confederates. This surprising action on the second day, for which Colonel Chamberlain won the Congressional Medal of Honor, stopped the Confederate assault on the far left of the Union line, saving it from collapse. That decision to charge, and the Maine men’s willingness to do it, likely saved the battle for the Union, and maybe even the war.

5 20th Maine monument 101215This is the monument to the 20th Maine at the charge site on Little Round Top.

6 Pickett Field 1011215Above is a view from the Union line on Cemetery Ridge westward across the fields to Seminary Ridge, which was occupied by the Confederates. On the third and last day of the battle, General Robert E. Lee ordered General James Longstreet to organize a general attack across these fields against the center of the Union line here. This is known to history as Pickett’s Charge. It was a foolish move, and everyone but Lee seemed to know that it was a hopeless, murderous gesture. The failure of this charge marked the end of the battle. General Lee retreated the next day.

7 20th Mass monument Gettysburg frontI was taken by this unusual monument to the 20th Massachusetts Infantry, which was one of the Union units that repulsed Pickett’s Charge on the third day of battle. Rather than statuary, the veterans of the 20th Massachusetts chose to transport a large rock from a neighborhood of Boston to be placed on their spot of the battlefield. The message was, of course, that here stood men of Massachusetts rock who could not be moved.

8 20th Mass monument Gettysburg sideThe rock is known as Roxbury Puddingstone, more formally called the Roxbury Conglomerate. It is the official state rock of Massachusetts. (Do you know your state rock?)

9 Roxbury Conglomerate 101215This rock contains a jumble of clasts of different sizes and maybe a dozen compositions. It is Ediacaran in age and likely accumulated in deep-sea fans as turbidites that formed when gravity-driven slurries of sediment flowed down submarine slopes. Or you can believe another story told in an 1830 poem by the future Supreme Court Justice Oliver Wendell Holmes, Jr., called “The Dorchester Giant“, who fed his rowdy family “a pudding stuffed with plums” that they flung about, leaving us the fossil evidence. Holmes served as an officer in the 20th Massachusetts.

References:

Brown, A. 2006. Geology and the Gettysburg Campaign. Pennsylvania Geological Survey Educational Series 5, published by the Commonwealth of Pennsylvania/Department of Conservation and Natural Resources/ Bureau of Topographic and Geological Survey: 14 pp.

Murray, J.M. 2014. On a Great Battlefield: The Making, Management, and Memory of Gettysburg National Military Park, 1933–2012. Univ. of Tennessee Press.

Newman, R.J. 2015. When the secular is sacred: The Memorial Hall to the Victims of the Nanjing Massacre and the Gettysburg National Military Park as pilgrimage sites. Global Secularisms in a Post-Secular Age 2: 261-270.

Weeks, J. 1998. Gettysburg: Display window for popular memory. The Journal of American Culture 21: 41-56.

Weeks, J. 2003. Gettysburg: Memory, market, and an American shrine. Princeton University Press.

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