Although laser vaporization of aerosol particles plays an important role in aerosol mass spectrometry, relatively little is known about disposal of excess energy in the degrees of freedom of the gas-phase species. A two-laser scheme, in which an infrared laser vaporizes aerosol particles prior to ionization of the vapor plume by a vacuum-ultraviolet laser, permits the determination of the internal energy of the neutral molecules created in laser vaporization. In this work, the fragmentation patterns of vacuum UV (VUV) photoionization mass spectra of ethylene glycol, in conjunction with photoelectron-photoion coincidence (PEPICO) measurements, determines the internal energy of gas-phase molecules created in the CO2 laser vaporization of neat ethylene glycol particles and ethanol particles mixed with trace ethylene glycol. The internal energy ranges from 1300 to 10250 cm-1 for CO2 laser powers between 25 and 112 mJ/pulse. For neat ethylene glycol, the rate with which the internal and kinetic energy grows with laser power increases sharply above 65 mJ/pulse, consistent with a change in vaporization mechanism from thermal to explosive. Monitoring the total ion signal as a function of the delay between the CO2 and VUV lasers provides an estimate of the relative kinetic energy of the vaporized molecules. At high laser fluences, the estimated translational energy is greater than the corresponding internal energy, indicative of vibrational cooling in the vapor plume. Ethanol particles containing 1.0% ethylene glycol produce similar results, with the transition in heating rate occurring at a lower temperature. The simplicity of the fragmentation pattern in these spectra and the broad range of temperatures that can be measured in this fashion make ethylene glycol an excellent "chemical thermometer" for reactions initiated by the laser heating of aerosol particles.
This report describes the geology of the bedrock strata at the Roade railway cutting (a Site of
Special Scientific Interest), near Northampton, exposed by engineering works between 2006 and
2010 and made available to the BGS for detailed examination. Strata exposed previously during
engineering works between 2005 and 2006 (engineering phases Priority 1 & 2) are described in a
companion report (Barron and Woods, 2010). The exposed strata, totalling about 8 m in
thickness, belong entirely to the Blisworth Limestone Formation of the Great Oolite Group,
which is of Mid Jurassic age. Neither the base nor top of the formation are exposed. The current
report includes text descriptions and graphic sections of the localities examined, a plan of the
cutting showing locations and the distribution of the strata with correlations, close-up
photographs of the bedrock exposed, and photographic panoramas of the cutting sides. It also
includes an assessment of the exposed strata in terms of their sedimentary facies and lateral
variability.
Known more for its literary connections with Jane Austen
and the gardens of the naturalist Gilbert White at Selborne,
the Alresford district’s typically gentile English countryside
seen in the Alresford district is fundamentally a product of
the underlying geology. Commencing in the east, a journey
westwards begins on the low lying sandy heaths and heavy
clay pastureland around Bordon and Woolmer Forest,
developed from the Lower Cretaceous sands and clays.
Further south-east around Petersfield, the characteristic
ridge and vale country is founded on the alternating sands
and clays of the Lower Cretaceous Hythe and Sandgate
formations.
R ising steeply above the lowlands is the indented and
landslipped Upper Greensand scarp, behind which the land
slopes gently down to small villages such as Selborne and
East Worldham before rising steeply again up the Chalk
escarpment which forms perhaps the most striking feature.
This scarp, running north–south across the sheet district
effectively divides the region into two. Above the scarp the
high hills capped by clay-with-flint around Medstead and
Four Marks gently descend eastward down the long gentle
dip slopes of the Chalk to the headwaters of the Itchen
around New Alresford. The majority of the East Hampshire
Downs with its dry valleys and gently rolling hills is underlain
by the Chalk.
T he landscape seen today is the result of a very long
geological history which stretches back to the Early Jurassic
and beyond. The rocks at surface and those beneath the district
give valuable information for the understanding of such
major earth history events as the opening of the Atlantic and
the Channel Basin, the drowning of most of Europe during
the Cretaceous Period, the Alpine earth movements and the
wide climatic variations in our most recent past.
T hese events have also created the conditions for the
development of oil and gas and their entrapment in the rocks
at depth, a feature which manifests itself in the ‘nodding
donkeys’ pumping oil to the surface at places such as
Humbly Grove just to the north of the district.
This book brings together information that results from
research on the ground beneath the streets of London. It
describes the geological strata, how they came to be there,
and how they impinge on the life of those who live and
work in the city, in its maintenance and sustainable development.
The development of London is intimately tied to the
ground conditions. The original settlement was originally
located at a crossing point on the River Thames in an
area of dry land where sand and gravel banks were surrounded
by rather boggy marshland.
A ready supply of
gravel and brick clay helped with the early infrastructure
development, and much later the extensive underground
tunnel network grew because of the ease of excavating
the London Clay. Water was always readily available, initially
from riverside springs and later, in larger volumes,
from underground Chalk.
This explanation of the strata that underlie London
gives an insight into the geological history of the last 500
million years. Over the past 200 years, boreholes have
explored the deeper layers and countless geologists have
systematically recorded the near-surface strata in quarries
and excavations. The geological history includes periods
of earth movement, inundations by the sea, the development
of coastal mudflats and the effects of great ice
ages.
Exploration for oil and gas in the North Sea has benefited
from an understanding of the rocks beneath
London, and their geological history. Effective use of
water resources, efficient ground investigation for new
buildings and infrastructure, and sustainable planning
and development are all founded on the use of information
about the condition and structure of the ground.
This book provides the background information for the
maintenance of good practice in these activities, and
illustrates some aspects of the ground that have in the
past caused difficulties.
Environmental concerns such as the legacy of contamination,
sea level rise as a consequence of global climate
change, and the recycling of water are issues that will
increase in importance in this century. Basic data, fundamental
for dealing with these concerns are presented in
this book, and on the associated 1:50 000 scale geological
maps for London.
This report describes the geology of the bedrock strata exposed by engineering works between
2005 and 2006 and made available to BGS at the Roade railway cutting, near Northampton. The
strata, totalling about 8.5 m in thickness, belong entirely to the Blisworth Limestone Formation
of the Great Oolite Group, which is of Middle Jurassic age, but the base and top of the formation
are not exposed. The report includes text and graphic sections of the localities examined, a plan
of the cutting showing locations and the distribution of the strata, close-up photographs of the
bedrock exposed, and photographic panoramas of the cutting sides.
Palaeokarst within the Lower to Middle Ordovician Goodwin Formation, Pogonip Group (upper Ibexian-lower Whiterockian) was examined in detail at Meiklejohn Peak, Nevada USA in order to determine its origin, evolution, and relationship to sea level change. Detailed outcrop and petrographic examination of dolostone breccias and host rock reveals that palaeokarst was formed and affected by two distinct cycles of sea level change. A relative transgression resulted in deposition of lagoonal, ooid shoal, and shallow subtidal facies as sea level rose. Exposure of the carbonate platform led to the formation of multiple phreatic caves below the water table, as well as the development of numerous vadose conduits from the downward percolation of meteoric waters. Vadose water flow through early cave-wall and cave-roof collapse breccias resulted in rounding of smaller breccias clasts via physical transport and corrosion, while subsidence of subsurface karst led to the formation of a palaeodoline at the exposure surface. A second relative transgression deposited lagoonal sediments over the older karst; subsequent re-exposure of the carbonate platform resulted in the development of small breccia pockets as well as grikes within the youngest lagoonal sediments, and may have led to further corrosion of the older, deeper subsurface karst. The distal location of the study area within the carbonate platform suggests karst formation was the result of a substantial drop in relative sea level; the presence of multiple generations of palaeokarst imply that at least two higher-frequency cycles of sea-level change overprint the larger regression.
BGS work on the Chalk Group of the Thames Basin has amassed large quantities of geological
information about thickness, facies, marker-beds, biostratigraphy and structure, only a small part
of which is incorporated into the geological map. More recently there has been wider use and
interpretation of borehole data to underpin the development of 3D geological models. There is a
pressing need to organise these disparate data in a way that can easily be compared and
interrogated, as well as to capture the results of relevant published research outside BGS. This
project addresses this need by creating a new spatial database, the Thames Chalk Information
System (TCIS). The database uses ArcGIS technology to display key information layers about
the Chalk. As well as standard topographical and geological information, TCIS includes layers
describing: Group, Subgroup, and formational thickness; structural data; detailed stratigraphical
data; coverage of 3D geological models that include units or surfaces of the Chalk Group;
regions where data coverage limits our understanding of the Chalk. Hydrogeological data is
currently being compiled as part of a related project; it is not currently available for
incorporation into the TCIS, but will eventually be added. Basic information about the content
and methodology used to compile the data in the TCIS is outlined in the main body of this report.
Hydrogeological data was delivered through a separate project, and its features are the subject of
a separate report. The aim of this report is to provide sufficient background information to allow
meaningful use of the TCIS database; there is no new data interpretation.
This report describes the geological modelling of the Chalk in the North Downs of East Kent,
within the catchment of River Great Stour and eastwards to the coast, including the Isle of
Thanet. This work was funded by the Environment Agency to support investigations of the local
hydrogeology and thereby to enhance catchment management.
The whole area is underlain by the Upper Cretaceous Chalk Group, with the Palaeogene
succession of the Thanet Sand Formation, the Lambeth Group and the Thames Group overlying
it in the northern and central eastern parts.
The project included a desk study revision of the Chalk of the North Downs, using the new
Chalk lithostratigraphy. The revisions to the geology are shown on the 1:50 000 scale geological
map which accompanies this report. Together with evidence from boreholes and from seismic
surveys, the new outcrop patterns have been incorporated into a geological model, using both
computer software (EarthVision) and manual methods.
The introduction describes the background to the project. The second chapter describes the
sources for the data used in the model: published and unpublished geological maps, borehole
records (both lithological and geophysical), seismic surveys, biostratigraphic records, digital
topographic information, and the published literature.
Each Chalk formation present in the area is then briefly described in the third chapter, noting its
relationship to the older lithostratigraphic divisions, and to biostratigraphic zones. The local
Chalk succession extends from the base of the Chalk Group to the Newhaven Chalk Formation,
here represented by the Margate Chalk Member. Evidence for the thickness of each formation is
reviewed.
The early Palaeogene formations (the Thanet Sand, Upnor, Harwich and London Clay
formations) are also briefly described (Chapter 4) and the local superficial deposits mentioned,
with references to detailed descriptions (Chapter 5). Apart from minor adjustments to the outcrop
of the basal Palaeogene surface, no revision of these formations was done for this study.
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