With news coming this week that NASA has confirmed the presence of flowing saltwater on the surface of Mars, the hunt for life on the Red Planet has new momentum.
“One of the many reasons this is exciting is that life as we currently know it requires water,” said Alison Olcott-Marshall, assistant professor of geology at the University of Kansas. “So the fact that it’s present at Mars means that the most basic and universal requirement for life was fulfilled.”
In the journal Astrobiology, Olcott-Marshall recently has published an analysis of Eocene rocks found in the Green River Formation, a lake system extending over parts of Colorado, Utah and Wyoming.
Marshall and co-author Nicholas A. Cestari, a masters student in her lab, found these Green River rocks have features that visually indicate the presence of life, and they argue that probes to Mars should identify similar indicators on that planet and double-check them through chemical analysis.
“Once something is launched into space, it becomes much harder to do tweaks — not impossible, but much, much harder,” Olcott-Marshall said. “Scientists are still debating the results of some of the life-detection experiments that flew to Mars on the Viking Missions in the late ’70s, in a large part because of how the experiments were designed. Looking at Earth-based analogs lets us get some of these bumps smoothed out here on Earth, when we can revise, replicate and re-run experiments easily.”
The researchers examined cored samples of rock from 50 million years ago that included sections of “microbial mats.”
“Microbial mats are essentially the microbial world’s version of apartment buildings — they are layered communities of microbes, and each layer represents a different metabolic strategy,” Olcott-Marshall said. “Generally, the photosynthetic microbes are at the top, and then every successive layer makes use of the waste products of the level above. Thus, not only does a microbial mat contain a great deal of biology, but a great number of chemicals, pigments and metabolic products are made, which means lots of potential biosignatures.”
At times during the Eocene, the Green River Formation’s water chemistry purged fish and other organisms from the lake, providing room for these microbes to thrive.
“During these times, ‘microbialites’ formed — these are rocks thought to be made by microbial processes, essentially the preserved remnants of microbial mats. The Green River Formation has a wide variety of these structures, and these features are why we went looking in these rocks, as microbialites are one life-detection target on Mars.”
First, the researchers visually inspected the cored samples for signs of biology by identifying geological signs associated with microbialites — such as “stromatolites.”
“These are things like finely laminated sediments, where each lamination follows the ones below, or signs of cohesive sediment, things like layers that roll over onto themselves or are at an angle steeper than what gravity would allow,” Olcott-Marshall said. “These are all thought to be signs that microbes are helping hold sediment together.”
If visual examination pointed to the presence of biology in sections of the rock cores, the researchers looked to confirm the presence of life. They powdered those rock samples in a ball mill, and then used hot organic solvents like methanol to remove any organic carbons that might have been preserved in the rocks. That solvent was then concentrated and analyzed with gas chromatography/mass spectroscopy.
“GC/MS allows an identification of compounds, including organic molecules, preserved in a rock,” Olcott-Marshall said. “Viking was the first time that a GC/MS was sent to Mars, and there is one up there right now on Curiosity collecting data.”
Through GC/MS, the researchers determined that rock structures appearing to be biological indeed hosted living organisms millions of years ago: analysis showed the presence of lipid biomarkers.
“A lipid biomarker is the preserved remnant of a lipid, or a fat, once synthesized by an organism,” Olcott-Marshall said. “These can be simple or very complex. Different organisms make different lipids, so identifying the biomarker can often allow a deeper understanding of the biota or the environment present when a rock was formed. These are a type of biosignature.”
The researchers said their results could be a powerful guide for sample selection on Mars.
“There is a GC/MS on Curiosity right now, but there are only nine sample cups dedicated for looking for biomarkers like these,” Olcott-Marshall said. “It’s crucial those nine samples are ones most likely to guarantee success.
Additionally, one of the goals of the planned 2020 rover mission is to identify samples for caching for eventual return to Earth. The amount of sample that can be returned is likely very small, thus, once again, doing our best to guarantee success is very important. What this shows is that we can use visual inspection to help us screen for these samples that are likely to be successful for further biosignature analysis.”
She said microbial and non-microbial rocks are found in similar environments, with identical preservation histories for millions of years, and many of the same chemical parameters, such as amounts of organic carbon preserved in the rocks.
“The only difference is that one rock is shaped in a way people have associated with biology, and sure enough, those rocks are the ones that seem to preserve the biosignatures, at least in the Green River,” she said.
The study is the first to provide indications that mummification may have been a wide-spread funerary practise in Britain.
Working with colleagues from the University of Manchester and University College London, Dr Tom Booth analysed skeletons at several Bronze Age burial sites across the UK. The team from the University of Sheffield’s Department of Archaeology found that the remains of some ancient Britons are consistent with a prehistoric mummy from northern Yemen and a partially mummified body recovered from a sphagnum peat bog in County Roscommon, Ireland.
Building on a previous study conducted at a single Bronze Age burial site in the Outer Hebrides, Dr Booth used microscopic analysis to compare the bacterial bioerosion of skeletons from various sites across the UK with the bones of the mummified bodies from Yemen and Ireland.
Archaeologists widely agree that the damp British climate is not favourable to organic materials and all prehistoric mummified bodies that may be located in the UK will have lost their preserved tissue if buried outside of a preservative environment such as a bog.
Dr Booth, who is now based at the Department of Earth Sciences at London’s Natural History Museum, said: “The problem archaeologists face is finding a consistent method of identifying skeletons that were mummified in the past – especially when they discover a skeleton that is buried outside of a protective environment.
“To help address this, our team has found that by using microscopic bone analysis archaeologists can determine whether a skeleton has been previously mummified even when it is buried in an environment that isn’t favourable to mummified remains.
“We know from previous research that bones from bodies that have decomposed naturally are usually severely degraded by putrefactive bacteria, whereas mummified bones demonstrate immaculate levels of histological preservation and are not affected by putrefactive bioerosion.”
Earlier investigations have shown that mummified bones found in the Outer Hebrides were not entirely consistent with mummified remains found elsewhere because there wasn’t a complete absence of bacterial bioerosion.
However, armed with a new technique, the team were able to re-visit the remains from the Outer Hebrides and use microscopic analysis to test the relationship between bone bioerosion and the extent of soft tissue preservation in bone samples from the Yemeni and Irish mummies.
Their examinations revealed that both the Yemeni and Irish mummies showed limited levels of bacterial bioerosion within the bone and therefore established that the skeletons found in the Outer Hebrides as well as other sites across Britain display levels of preservation that are consistent with mummification.
The research team also found that the preservation of Bronze Age skeletons at various sites throughout the UK is different to the preservation of bones dating to all other prehistoric and historic periods, which are generally consistent with natural decomposition. Furthermore, the Sheffield-led researchers also found that Bronze Age Britons may have used a variety of techniques to mummify their dead.
Dr Booth added, “Our research shows that smoking over a fire and purposeful burial within a peat bog are among some of the techniques ancient Britons may have used to mummify their dead. Other techniques could have included evisceration, in which organs were removed shortly after death.
“The idea that British and potentially European Bronze Age communities invested resources in mummifying and curating a proportion of their dead fundamentally alters our perceptions of funerary ritual and belief in this period.”
The research also demonstrates that funerary rituals that we may now regard as exotic, novel and even bizarre were practised commonly for hundreds of years by our predecessors.
Also, this method of using microscopic bone analysis to identify formerly-mummified skeletons means that archaeologists can continue searching for Bronze Age mummies throughout Europe.
“It’s possible that our method may allow us to identify further ancient civilisations that mummified their dead,” Dr Booth concluded.
New research suggests that ancient marine animals took millions of years longer to stir up the sea floor than previously thought. The timing has implications for the chemical composition of Earth’s early oceans and atmosphere, and for the formation of ocean ecosystems.
The process of mixing sediments by burrowing animals is known as “bioturbation.” It is a hallmark of the modern ocean floor, shaping the ecological character of marine environments around the world. For years, scientists thought bioturbation commenced in earnest with the Cambrian Explosion, 541 million years ago, when the complexity and diversity of animal species began to expand dramatically.
But that wasn’t the case. In a new study published in the journal Nature Geoscience, researchers found that major bioturbation did not occur until at least 120 million years later, during the late Silurian Period.
“We found it particularly intriguing that although burrowing animals colonized seafloor sediments very early in animal history, there was such a substantial lag between colonization and intensive, modern-style sediment mixing,” said Lidya Tarhan, a postdoctoral associate at Yale and lead author of the study.
Tarhan and her colleagues based their analysis on extensive fieldwork in the United Stated, Canada, Spain, and Australia. The team studied trace fossils — the trails, tracks and burrow marks left behind by animals — and sedimentary conditions under which the trace fossils were formed and preserved. The research team concentrated on a single type of environment, the shallow ocean seafloor.
“No previous study had ever attempted to do all these things,” Tarhan said. “It was our multi-pronged approach that yielded unprecedented insight into what was previously a largely intractable question: When and by what means and how rapidly did burrowing animals start to engineer the seafloor?”
Among the burrowing animals responsible for this record were trilobites, crustaceans, and a variety of worm-like creatures.
The researchers also propose that delayed bioturbation may have been responsible for regulating marine sulfate and atmospheric oxygen levels. A previously proposed drop in surface oxygen levels may be tied to the onset of extensive bioturbation, given that “oxygen is directly tied to the burial of organic carbon,” Tarhan said. “Less burial of organic carbon, due to bioturbation, means that more oxygen is used to respire or burn through that carbon, and thus oxygen decreases.”
Additional co-authors of the study are Noah Planavsky, a Yale assistant professor of geology and geophysics; Mary Droser of the University of California-Riverside; and David Johnston of Harvard.Written by Jim Shelton
The two Confederate Brooke rifle cannons (11.8 and 12.25 feet each) and one captured Union Dahlgren cannon (8.9 feet) were artillery of the CSS Pee Dee, a 150-foot Confederate gunboat, a Macon-class gunboat built to patrol waterways and protect the coast.
“The recovery of these three cannons — the complete armament of a Confederate gunboat — offers unique insight in the arming and intended role of this warship to contest the Union blockade off the coast of South Carolina and to perhaps engage in high seas raiding against Northern merchant vessels,” says James Spirek, an underwater archaeologist with the university’s South Carolina Institute for Archaeology and Anthropology (SCIAA).
Just three months after it launched, the CSS Pee Dee’s career was cut short on March 15, 1865, in response to U.S. Gen. William T. Sherman’s northward advance to North Carolina. Fearing that the gunboat might fall into enemy hands, commanders ordered the cannons thrown overboard into the river before the ship was set ablaze and scuttled.
The UofSC team began its search for the Confederate Mars Bluff Navy Yard and the elusive 150-foot Confederate gunboat CSS Pee Dee with its cannons in March 2009. Their efforts were greatly facilitated by earlier work conducted at the site, particularly by a private research group, the CSS Pee Dee Research and Recovery Team, operating under an archaeological license issued by SCIAA in the late 1990s.
The Mars Bluff Navy Yard was one of seven Confederate naval yards that were located inland so gunboats and support vessels for the war could be built and protected from U.S. forces. It was chosen for its inland location on the east side of the river in Marion County, proximity to the railroad, water communication with Charleston via Georgetown and the abundance of ash, oak and pine lumber.
Historic records indicated that the CSS Pee Dee had two Confederate Brooke rifle cannons and one captured Union Dahlgren, smooth-bore, nine-inch shell cannon on board at the time of the ship’s sinking. The university archaeology team also knew that the wreck was broken up by a U.S. Army Corps of Engineers dredging operation in 1906 and parts – propellers, engines and a boiler – were recovered in salvage operations in later decades.
Quickly after the UofSC team began its archaeological work, one of two Brooke rifle cannons (6.4 inch) and the Dahlgren cannon were located. The discovery of the wreck itself came 18 months later using sonar. Ripples on the sand where sediment had built up over debris and magnetic “hits” in straight lines depicting the iron bolts along bedding timbers revealed the remnants of the CSS Pee Dee.
The underwater work wasn’t easy, with the team often working in conditions of high, near-flood water levels in the river and with a river bottom of timber from past logging operations that resembled an underwater field of “pick-up sticks.”
“In addition to logs carpeting the bottom, the turbid waters and the varying depth of burial of the cannons and the other artifacts caused us to move slowly and systematically to document the assemblage of the discarded materials from the ship and navy yard,” Spirek says.
While underwater archaeologists were working in the Great Pee Dee River, fellow archaeologist Jon Leader and UofSC students were working along the banks and fields in search of the naval yard using ground-penetrating radar and other remote-sensing technologies. By June 2009, Leader identified where the buildings of the naval yard once stood, the dry dock and excavated artifacts, such as ceramics, glass and nails, that provided clues to the activity areas of Mars Bluff, which was operated as a Confederate States of America (CSA) stronghold from 1862 to 1865.
“The students and volunteers were key to deploying the geophysics and defining the hidden below ground portions of the naval yard. We accomplished what would have been six months of traditional investigation in a matter of weeks,” says Leader, who serves as South Carolina’s state archaeologist.
Spirek said the elusive third cannon was finally located in 2012 when property owners Glenn Dutton and Rufus Perdue took advantage of low water and ventured into the stream with a metal detector. Spirek confirmed that the large object was the missing 7-inch Brooke rifle.
The project was funded in part by grant exceeding $200,000 from the Drs. Bruce and Lee Foundation in Florence, S.C.
The newly raised cannons will be transported to the Warren Lasch Conservation Center in North Charleston, S.C., where they will undergo conservation for approximately two years. The center is the facility conserving the Confederate submarine H.L. Hunley. Once complete, the trio of cannons from the CSS Pee Dee will return home to be on permanent outdoor display at the newly constructed U.S. Department of Veterans Affairs building in Florence.
The South Carolina Institute for Archaeology and Anthropology, part of the College of Arts and Sciences, was established in 1963 as a University of South Carolina research institute and a cultural resource management agency of the state of South Carolina.
CSS Pee Dee Cannons Recovery Project
University of South Carolina archaeologists recovered three cannons from the Confederate gunboat CSS Pee Dee from the Great Pee Dee River on Tuesday (Sept. 29). The cannons will undergo conservation for two years at the Warren Lasch Conservation Center in North Charleston, S.C. The cannons will return to Florence, S.C., for outdoor display at the newly constructed U.S. Department of Veterans Affairs building.
The three cannons represent the premier naval weapons from the Civil War.
6.4-inch Brooke rifle:
• Model: No. S-53, cast in Selma, Ala., April 29, 1863, delivered to Peedee, S.C., on July 13, 1863
• Overall length: 141.85 inches (11.8 feet/3.6 meters)
• Bore Length: 117 inches (9.75 feet/3 meters)
• Weight 10,600 pounds (4,808 kg)
7-inch Brooke rifle:
• Model: No. S-46, cast in Selma, Ala., on Oct. 12, 1863, delivered to Peedee, S.C. on July 3, 1863
• Overall Length: 147 inches (12.25 feet/3.7 meters)
• Bore Length: 130-136 inches (10.8-11.3 feet/3.2-3.4 meters)
• Weight: 15,000 pounds (6,803 kg)
9-inch Dahlgren smoothbore:
• Model: FP-513, cast in Fort Pitt, Penn.; based on inspector mark, cast mid-1862
• Marks: On trunnion-JMB; on breech serial number
• Overall Length: 131.5 inches (10.9 feet /3.3 meters)
• Bore Length: 107 inches (8.9 feet/2.7 meters)
• Weight: 9,000-9,200 pounds (4,082-4,173 kg)
A history of the Mars Bluff Navy Yard and CSS Pee Dee
By James Spirek, South Carolina Institute for Archaeology and Anthropology
On March 4, 1862, the secretary of the Confederate Navy, Stephen Mallory, requested the immediate construction of naval yards on inland waters throughout the South in an effort to protect newly built warships from Union forces blockading the Southern coast. In South Carolina, Mars Bluff on the Great Pee Dee River was chosen for the site of that state’s inland Confederate shipyard. Adjacent to the Wilmington-Manchester Railroad and a major ferry crossing, the navy yard had good water communication with Georgetown and Charleston via Winyah Bay, and the surrounding terrain held vast stands of ash, oak and pine necessary for a successful shipbuilding facility.
In its two years of operation, the Mars Bluff Navy Yard produced a number of vessels including a 150-foot long Macon-class gunboat named after the river on which it was constructed. CSS Pee Dee, was a twin-screw, steam and wind-powered Macon-class gunboat with a 7.5-foot draft similar in design to CSS Chattahoochee, the remains of which reside in the National Civil War Naval Museum at Port Columbus, Ga. The 150-foot long and 25-foot wide deck of the Pee Dee supported three large guns. At the bow and stern were two Brooke rifle cannon, one firing a 6.4-inch shell, the other, a 7-inch round. A 9-inch smoothbore Dahlgren was fitted amidships.
All three guns were mounted on carriages that could pivot 180 degrees for a prodigious arc of fire. While the Brooke rifles were considered by many to be the most accurate of the Civil War-era naval artillery, naval officers often preferred smoothbore guns like the Dahlgren for naval engagements, which were frequently fought at close quarters. The smoothbores had greater smashing power, and the projectiles could be skipped over the surface of the water (ricochet fire) to great effect. Also, the smooth gun tubes were capable of firing a wide variety of projectiles, including round shot, shell, shrapnel, canister and grape shot.
The Pee Dee’s complement consisted of 91 officers and crew, two-thirds of that number filling out two shifts devoted to manning and maintaining the three guns. The gunboat was launched in January 1865, and due to the rapidly deteriorating military situation in the state, it was too late to fully outfit the vessel and move it down the nearly 100 river miles to Winyah Bay. U.S. forces under the command Gen. William T. Sherman were moving northward through the state and by February were to take Georgetown, effectively blocking the gunboat’s route to the Atlantic.
In early March, Lt. Oscar Johnston, CSN, the Pee Dee’s commander moved the gunboat upstream to Cheraw, S.C., to cover the crossing of the Great Pee Dee River of Confederate troops under the command of Gen. William J. Hardee to join Gen. Joseph E Johnston’s forces in North Carolina for what was to become the last major battle of the war.
Thereafter, Lt. Johnston, turned the vessel (no mean feat in a river that was scarcely wider than the ship was long) and returned to Mars Bluff. On March 2, 1862, as Cheraw succumbed to Sherman’s forces, Lt. Edward Means, commander of the Mars Bluff Navy Yard, was given the order to destroy the navy yard and vessels. Two weeks later, on March 15, the guns of the Pee Dee were jettisoned into the river and the gunboat floated downstream of the railway bridge, set afire and blown up.
At various times throughout the 20th century, when the river was exceptionally low, various groups’ recovered components of the gunboat. In 1925, the screw propellers were recovered; then in 1954, machinery from the hull. The screw propellers are on display in the Florence County Museum, while the machinery and hull structure removed in the 1950s have disappeared and become the subject of local lore.
In the last 50 years, several projects were initiated to locate and recover the Pee Dee’s guns. During the 1990s, a group named the CSS Pee Dee Research and Recovery Team, headed by Ted Gragg and Bob Butler, received an intensive survey license from South Carolina Institute of Archaeology and Anthropology (SCIAA), to conduct an underwater survey of the near-shore river bottom at the yard.
Their purpose was to map the river bottom in front of the navy yard site and recover artifacts to exhibit in Gragg’s South Carolina Civil War Museum to tell the story of the Mars Bluff Navy Yard. The team recovered numerous artifacts associated with navy yard activities, as well as logging operations before and after the Confederate occupation of the site. Their exhibition and site plans provide a tantalizing glimpse of the wealth of artifacts either discarded or eroded into the river from the bluff during the last 150-plus years. The plans also indicate the presence of two gun tubes identified as a 6.4-inch Brooke rifle and a 9-inch Dahlgren.
In 2009, the Maritime Research Division and Office of State Archaeologist of SCIAA received funding from the Drs. Bruce and Lee Foundation, a private philanthropic organization based in Florence, to document the land and underwater features of the navy yard. In addition, the funds covered efforts to recover, conserve, and display the three cannons from the CSS Pee Dee.
Working in partnership with the Program in Maritime Studies at East Carolina University underwater archaeologists and students conducted archeological investigations on land and underwater, recording the two cannons and a number of Brooke rifle shells and other munitions, along with sundry items associated with the navy yard and modern debris. Efforts to locate the 7-inch Brooke rifle proved unsuccessful and the cannon remained elusive at the end of the field school.
In late 2012, the property owners adjacent the jettisoned cannons, Glenn Dutton and Rufus Perdue, taking advantage of low water, waded around the site with a metal detector. Further out into the stream, the pair located a large magnetic anomaly buried under the sand. They notified SCIAA who investigated and identified the source of the anomaly as the 7-inch Brooke rifle. With the discovery of the last cannon plans began in earnest to recover the cannons.
Of historical interest is the positive identification of the 9-inch Dahlgren smoothbore as one of the guns recovered from the USS Southfield. The Union gunboat was rammed and sunk by the ironclad ram CSS Albemarle in the Roanoke River near Plymouth, N.C., on April 18, 1864.
Confederate forces recovered the armament of the sunken Union gunboat, which included five 9-inch Dahlgren smoothbores. Of these five cannons, three stayed in Plymouth, while two were shipped to other destinations. Apparently, one was shipped south to the Mars Bluff Navy Yard to supplement the two Brooke rifles aboard the Confederate gunboat. The identity of this cannon has been confirmed that it was one of the cannons recovered from the sunken USS Southfield. The smoothbore’s serial number “FP 513, stands for Fort Pitt, the foundry where the cannon was cast in 1862.
As the cannons are managed by the Administrator of General Services (GSA) on behalf of the American people, a loan agreement was signed between the Florence County Museum, SCIAA and Florence County to curate and display the cannons. The contractor to recover the three cannons is Long Bay Salvage Co., owned by Glenn Dutton and Rufus Perdue, experienced heavy-equipment operators with familiarity in recovering large cannons from a shipwreck off the South Carolina coast.
Once the cannons are recovered they will be transported to the Warren Lasch Conservation Center in North Charleston, S.C., also the facility treating the Confederate submarine H.L. Hunley. Following an estimated two-year treatment period, the cannons will return to Florence for display at the newly constructed U.S. Department of Veterans Affairs facility.
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