Groundbreaking report details status of US secondary Earth science education

The Center for Geoscience Education and Public Understanding at the American Geosciences Institute has released a landmark report on the status of Earth Science education in U.S. middle and high schools, describing in detail significant gaps between identified priorities and lagging practice.

The report, “Earth and Space Sciences Education in U.S. Secondary Schools: Key Indicators and Trends,” offers baseline data on indicators of the subject’s status since the release of the Next Generation Science Standards (NGSS) in April 2013. Establishing clear aims for the subject, the NGSS state that the Earth and Space Sciences should have equal status with the Life Sciences, Physical Sciences, Technology, and Engineering. However, the report shows that school districts and other organizations fail to assign the Earth Sciences this status.

Only one of the nation’s 50 states requires a year-long Earth/Environmental Science course for high school graduation, whereas 32 states require a Life Science course, and 27 require a Physical Science course, according to the report. Only six states require that students are taught Earth Science concepts as part of their graduation requirements. Detailed and analyzed are key indicators including:

  • presence of Earth Science topics in state and national standards;

  • consideration of Earth Science as a graduation requirement;

  • evaluation of Earth Science concepts on high-stakes assessments; and

  • acceptance of Earth Science courses for college admission.

Recommendations for better treatment of Earth Science subject matter include changes in the subject’s relevance to graduation requirements, the discipline’s presence on assessments, designation of Earth Science courses as laboratory courses, and establishment of an Advanced Placement Earth Science program.

First ever evidence of a comet striking Earth

This is an artist's rendition of the comet exploding in Earth's atmosphere above Egypt. -  Terry Bakker
This is an artist’s rendition of the comet exploding in Earth’s atmosphere above Egypt. – Terry Bakker

The first ever evidence of a comet entering Earth’s atmosphere and exploding, raining down a shock wave of fire which obliterated every life form in its path, has been discovered by a team of South African scientists and international collaborators.

The discovery has not only provided the first definitive proof of a comet striking Earth, millions of years ago, but it could also help us to unlock, in the future, the secrets of the formation of our solar system.

“Comets always visit our skies – they’re these dirty snowballs of ice mixed with dust – but never before in history has material from a comet ever been found on Earth,” says Professor David Block of Wits University.

The comet entered Earth’s atmosphere above Egypt about 28 million years ago. As it entered the atmosphere, it exploded, heating up the sand beneath it to a temperature of about 2 000 degrees Celsius, and resulting in the formation of a huge amount of yellow silica glass which lies scattered over a 6 000 square kilometre area in the Sahara. A magnificent specimen of the glass, polished by ancient jewellers, is found in Tutankhamun’s brooch with its striking yellow-brown scarab.

The research, which will be published in Earth and Planetary Science Letters, was conducted by a collaboration of geoscientists, physicists and astronomers including Block, lead author Professor Jan Kramers of the University of Johannesburg, Dr Marco Andreoli of the South African Nuclear Energy Corporation, and Chris Harris of the University of Cape Town.

At the centre of the attention of this team was a mysterious black pebble found years earlier by an Egyptian geologist in the area of the silica glass. After conducting highly sophisticated chemical analyses on this pebble, the authors came to the inescapable conclusion that it represented the very first known hand specimen of a comet nucleus, rather than simply an unusual type of meteorite.

Kramers describes this as a moment of career defining elation. “It’s a typical scientific euphoria when you eliminate all other options and come to the realisation of what it must be,” he said.

The impact of the explosion also produced microscopic diamonds. “Diamonds are produced from carbon bearing material. Normally they form deep in the earth, where the pressure is high, but you can also generate very high pressure with shock. Part of the comet impacted and the shock of the impact produced the diamonds,” says Kramers.

The team have named the diamond-bearing pebble “Hypatia” in honour of the first well known female mathematician, astronomer and philosopher, Hypatia of Alexandria.

Comet material is very elusive. Comet fragments have not been found on Earth before except as microscopic sized dust particles in the upper atmosphere and some carbon-rich dust in the Antarctic ice. Space agencies have spent billions to secure the smallest amounts of pristine comet matter.

“NASA and ESA (European Space Agency) spend billions of dollars collecting a few micrograms of comet material and bringing it back to Earth, and now we’ve got a radical new approach of studying this material, without spending billions of dollars collecting it,” says Kramers.

The study of Hypatia has grown into an international collaborative research programme, coordinated by Andreoli, which involves a growing number of scientists drawn from a variety of disciplines. Dr Mario di Martino of Turin’s Astrophysical Observatory has led several expeditions to the desert glass area.

“Comets contain the very secrets to unlocking the formation of our solar system and this discovery gives us an unprecedented opportunity to study comet material first hand,” says Block.

Methane out, carbon dioxide in?

A University of Virginia engineering professor has proposed a novel approach for keeping waste carbon dioxide out of the atmosphere.

Andres Clarens, an assistant professor of civil and environmental engineering at U.Va.’s School of Engineering and Applied Science, and graduate student Zhiyuan Tao have published a paper in which they estimate the amount of carbon dioxide that could be stored in hydraulically fractured shale deposits after the methane gas has been extracted. Their peer-reviewed finding was published in Environmental Science and Technology, a publication of the American Chemical Society.

The team applied their model to the Marcellus Shale geological formation in Pennsylvania and found that the fractured rock has the potential to store roughly 50 percent of the U.S. carbon dioxide emissions produced from stationary sources between 2018 and 2030. According to his estimate, about 10 to 18 gigatonnes of carbon dioxide could be stored in the Marcellus formation alone. The U.S. has several other large shale formations that could provide additional storage.

The researchers’ model is based on historical and projected methane production, along with published data and models for estimating the carbon dioxide capacity of the formations. Clarens said that production records are available for how much methane gas producers have already extracted from the Marcellus Shale, as well as estimates of how much more they expect to extract. That provides a basis for determining how much space will be left in the formation when the methane is gone, he said. Clarens said gas would be adsorbed into the pores of the shale and held securely.

“This would be a way of eating our cake and having it too,” Clarens said. “We can drill the shale, pump out the gas and pump in the carbon dioxide.. I think this will get policymakers’ attention.”

He said his work deals with the chemical feasibility of the idea, and that additional studies must be performed to examine the economical, political and logistical implication.

“My field is carbon management – high-pressure carbon dioxide chemistry,” he said. “Right now, we are emitting huge levels of carbon dioxide, and we need new ideas on ways to store the waste.”

Clarens, who said he has no connection with the oil and gas industry, knows some in the environmental movement oppose hydraulic fracturing because of possible risks to ground and surface waters. However, he thinks this type of extraction is inevitable in many places and it is important to preemptively develop new strategies for handling the environmental implications, especially those related to carbon dioxide.

“There are a lot of people who say we need to get away from carbon-based fuels, and that may be possible in a few decades, but right now, fossil fuels power everything,” he said. “Finding ways to harvest these non-conventional fossil fuel sources without contributing to climate changes is a difficult but important challenge.”

Clarens said he believes he and Tao are the first researchers to propose this strategy. He hopes this paper will contribute to a discourse on how best to responsibly develop this booming resource.

Clarens, who received his doctorate from the University of Michigan, did his undergraduate work at U.Va., receiving a bachelor’s degree in chemical engineering in 1999.

Subduction channel processes: New progress in plate tectonic theory

Two processes occur at the slab-mantle interface in continental subduction channel, with (a) physical mixing to produce the tectonic mélange of metamorphic rocks, and (b) chemical reaction of the overlying subcontinental lithospheric mantle (SCLM) wedge with aqueous fluid and hydrous melt from subducting continental crust. -  ©Science China Press
Two processes occur at the slab-mantle interface in continental subduction channel, with (a) physical mixing to produce the tectonic mélange of metamorphic rocks, and (b) chemical reaction of the overlying subcontinental lithospheric mantle (SCLM) wedge with aqueous fluid and hydrous melt from subducting continental crust. – ©Science China Press

The plate tectonic theory has been primarily developed in three stages. (1) From continental drift and seafloor spreading to oceanic subduction, laying a physical foundation of the plate tectonic theory. This was achieved by the recognitions that continents would be assembled to build a supercontinent Pangea with subsequent breakup to yield the present configuration, lithospheric plates buoyantly move on the asthenospheric mantle, and oceanic crust is subducted along trenches into the mantle. (2) From oceanic subduction to continental subduction and collision orogeny, with the first round of revolution to the plate tectonic theory due to the recognition of continental deep subduction to mantle depths. While deeply subducted oceanic crust was processed in the mantle and the returned to the surface by mafic magmatism, deeply subducted continental crust underwent ultrahigh pressure metamorphism at mantle depths and then exhumed to the surface as coherent mélanges. This provides a geodynamic framework of tectonic processes for continental accretion and assemblage through arc-continent and continent-continent collision orogenies. (3) From continental collision and marginal orogeny to intracontinental reworking, emphasizing the inheritance of orogenic materials in postcollisional stages. While continental collision results in continental accretion through marginal orogeny, intercontinental orogens are converted to intracontinental orogens. The deeply subducted continental crust is processed in subduction channel underlying the mantle wedge, with partial return to the surface. These have thrown new lights on developing the plate tectonic theory to encompass the continental tectonics, and thus directed further study toward solution to such questions as how thinning of the orogenic lithosphere and upwelling of the asthenospheric mantle affect postcollisional reworking of the intracontinental materials.

Finding of ultrahigh pressure index minerals such as coesite and diamond in metamorphic rocks of continental supercrustal protolith demonstrate that these rock were subducted to mantle depths for ultrahigh pressure metamorphism and then returned back to the surface. The recognition of continental deep subduction by Earth scientists has not only developed the plate tectonic theory, but also expanded the chemical geodynamics focusing on the recycling of crustal material. The study of ultrahigh pressure metamorphic rocks has made prominent progress in many aspects, achieving the recognitions that the processes of continental seduction and exhumation have caused not only various types of structural deformation and mineralogical reaction but also different extents of metamorphic dehydration and partial melting (Fig. 1). By means of studying various rocks in continental collision orogens, Earth scientists have set the geodynamic link between the subduction and exhumation of continental crust and the building of collision orogens. Furthermore, it is established that bulk melting of the deeply subducted continental crust gives rise to granitic rocks whereas partial melting of the subducting supracrustal rocks produces felsic melt that reacts with the overlying mantle wedge peridotite to generate fertile and enriched mantle sources for mafic magmatism after their storage in different periods.

A research team at School of Earth and Space Sciences in University of Science and Technology of China has taken the rocks of continental collision orogens as the object, and performed a great deal of investigations from field observations and laboratory analyses. This leads to a tectonic analysis of geological processes in continental subduction factory, which is published in Chinese Science Bulletin 2013 (26) in the title “Continental subduction channel processes: Plate interface interaction during continental collision”. Leader of this team is Professor ZHENG Yongfei, Academician of the Chinese Academy of Sciences at Key Laboratory of Crust-Mantle Materials and Environments. Major participants are Prof. ZHAO Zifu and Dr. CHEN Yixiang. Earth scientists of China have made a series of prominent progresses in the forefront and hotspot field of subduction channel, and their studies have exemplified successful applications of new techniques, new methods and new ideas to development of the plate tectonic theory.

The recognition of continental deep subduction and ultrahigh pressure metamorphism has provided not only a turning point in developing the plate tectonic theory, but also an excellent opportunity to study the time and mechanism of reworking continental lithosphere. It is intriguing to ask the following questions: (1) how are crustal slices detached at different depths and exhumed during continental subduction? (2) how do physical mixing and chemical reaction proceed between the deeply subducted crust and the overlying mantle wedge? (3) how are energy exchange and matter transfer realized at the plate interface of subduction zone? Prof. Zheng said, to study subduction channel processes, to determine the physical mixing and chemical reaction between the deeply subducted crust and the overlying mantle wedge under ultrahigh pressure conditions, and to understand the interaction at the plate interface of continental subduction zone and its associated fluid action and element transport, are a key to unravel such mysteries of Earth.

Gravity variations much bigger than previously thought

This image is an extract of the new high-resolution gravity map over Australia and South-East Asia. The map tells us about the anomalies in gravity, with red indicating strongly positive anomalies and blue negative anomalies. -  Christian Hirt
This image is an extract of the new high-resolution gravity map over Australia and South-East Asia. The map tells us about the anomalies in gravity, with red indicating strongly positive anomalies and blue negative anomalies. – Christian Hirt

A joint Australian-German research team led by Curtin University’s Dr Christian Hirt has created the highest-resolution maps of Earth’s gravity field to date — showing gravitational variations up to 40 percent larger than previously assumed.

Using detailed topographic information obtained from the US Space Shuttle, a specialist team including Associate Professor Michael Kuhn, Dr Sten Claessens and Moritz Rexer from Curtin’s Western Australian Centre for Geodesy and Professor Roland Pail and Thomas Fecher from Technical University Munich improved the resolution of previous global gravity field maps by a factor of 40.

“This is a world-first effort to portray the gravity field for all countries of our planet with unseen detail”, Dr Hirt said.

“Our research team calculated free-fall gravity at three billion points — that’s one every 200 metres — to create these highest-resolution gravity maps. They show the subtle changes in gravity over most land areas of Earth.”

The new gravity maps revealed the variations of free-fall gravity over Earth were much bigger than previously thought.

The Earth’s gravitational pull is smallest on the top of the Huascaran mountain in the South American Andes, and largest near the North Pole.

“Only a few years ago, this research would not have been possible,” Dr Hirt said.

“The creation of the maps would have required about 80 years of office PC computation time but advanced supercomputing provided by the Western Australian iVEC facility helped us to complete the maps within a few months.”

High-resolution gravity maps are required in civil engineering, for instance, for building of canals, bridges and tunnels. The mining industry could also benefit.

“The maps can be used by surveyors and other spatial science professionals to precisely measure topographic heights with satellite systems such as the Global Positioning System (GPS),” Dr Hirt said.

The findings of the research team from Curtin and Technical University Munich have recently appeared in the journal Geophysical Research Letters.