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Author(s): Wu, H; Fu, P; Frone, Z; White, MD; Ajo-Franklin, JB; Morris, JP; Knox, HA; Schwering, PC; Strickland, CE; Roberts, BQ; Vermeul, VR; Mattson, ED; Ingraham, MD; Kneafsey, TJ; Blankenship, DA | Abstract: Heat recovery from an enhanced geothermal system (EGS) is a complex process involving heat transport in both fracture networks and rock formations. A comprehensive understanding of and the ability to model the underlying heat transport mechanisms is important for the success of EGS commercialization but remains challenging in practice due to the generally insufficient characterization of EGS reservoirs. In the present study, we analyze an extensively monitored intermediate-scale EGS field experiment performed in a well-characterized testbed. The high-resolution, high-quality measurements from the field experiment enable the development of a high-fidelity model incorporating a well-constrained fracture network. Based on the field experiment, we investigate the complex heat transport processes in an EGS-relevant environment and validate the capability of a numerical approach in simulating these inherently coupled heat transport processes. A series of numerical simulations were performed to study the effects of different heat transport mechanisms, including thermal convection with fracture flow, thermal conduction in rock formations, and the Joule-Thomson effect. The agreement of thermal responses between field measurements and simulation results indicates that our numerical approach can appropriately model the heat transport processes pertaining to heat recovery from EGS reservoirs.

Author(s): Johnson, TC; Burghardt, J; Strickland, C; Knox, H; Vermeul, V; White, M; Schwering, P; Blankenship, D; Kneafsey, T

Compressional seismic (P‐wave) velocities were measured experimentally at different matric suctions and confining pressure states using a variety of sediments collected from the USDOE Hanford Site in southeastern Washington State. The P‐wave velocity was measured in variably saturated sediments using ultrasonic piezoelectric transducers, and matric suction was measured with a heat dissipation sensor. Desaturation of the samples occurred by means of evaporative drying. We propose a model to relate changes in P‐wave velocity to soil stress conditions using an effective stress formulation that includes capillary stress as well as adsorptive stress. We show that compressional wave velocities can be related to matric suction and confining stress using a model with five fitted parameters. A single set of parameters describing the relationship between effective stress and P‐wave velocity provide an excellent fit to data acquired on Hanford Formation samples. The results presented here suggest the utility of seismic methods for establishing low matric suction and flow conditions within variably saturated Hanford formation sediments, which could be applied at the field scale for evaluating the performance of environmental remediation efforts, such as soil desiccation and surface infiltration barriers.

Author(s): Fu, P; Schoenball, M; Ajo-Franklin, JB; Chai, C; Maceira, M; Morris, JP; Wu, H; Knox, H; Schwering, PC; White, MD; Burghardt, JA; Strickland, CE; Johnson, TC; Vermeul, VR; Sprinkle, P; Roberts, B; Ulrich, C; Guglielmi, Y; Cook, PJ; Dobson, PF; Wood, T; Frash, LP; Huang, L; Ingraham, MD; Pope, JS; Smith, MM; Neupane, G; Doe, TW; Roggenthen, WM; Horne, R; Singh, A; Zoback, MD; Wang, H; Condon, K; Ghassemi, A; Chen, H; McClure, MW; Vandine, G; Blankenship, D; Kneafsey, TJ | Abstract: The final version of the above article was posted prematurely on 16 July 2021, owing to a technical error. The final, corrected version of record will be made fully available at a later date.

Author(s): Schoenball, M; Ajo-Franklin, JB; Blankenship, D; Chai, C; Chakravarty, A; Dobson, P; Hopp, C; Kneafsey, T; Knox, HA; Maceira, M; Robertson, MC; Sprinkle, P; Strickland, C; Templeton, D; Schwering, PC; Ulrich, C; Wood, T; Ajo-Franklin, J; Baumgartner, T; Beckers, K; Blankenship, D; Bonneville, A; Boyd, L; Brown, S; Burghardt, JA; Chai, C; Chakravarty, A; Chen, T; Chen, Y; Chi, B; Condon, K; Cook, PJ; Crandall, D; Dobson, PF; Doe, T; Doughty, CA; Elsworth, D; Feldman, J; Feng, Z; Foris, A; Frash, LP; Frone, Z; Fu, P; Gao, K; Ghassemi, A; Guglielmi, Y; Haimson, B; Hawkins, A; Heise, J; Hopp, C; Horn, M; Horne, RN; Horner, J; Hu, M; Huang, H; Huang, L; Im, KJ; Ingraham, M; Jafarov, E; Jayne, RS; Johnson, TC; Johnson, SE; Johnston, B; Karra, S; Kim, K; King, DK; Kneafsey, T; Knox, H; Knox, J; Kumar, D; Kutun, K; Lee, M; Li, K; Li, Z; Mackey, P; Makedonska, N; Marone, CJ; Mattson, E; McClure, MW; McLennan, J; McLing, T; Medler, C; Mellors, RJ; Metcalfe, E; Miskimins, J | Abstract: Enhanced Geothermal Systems could provide a substantial contribution to the global energy demand if their implementation could overcome inherent challenges. Examples are insufficient created permeability, early thermal breakthrough, and unacceptable induced seismicity. Here we report on the seismic response of a mesoscale hydraulic fracturing experiment performed at 1.5-km depth at the Sanford Underground Research Facility. We have measured the seismic activity by utilizing a 100-kHz, continuous seismic monitoring system deployed in six 60-m length monitoring boreholes surrounding the experimental domain in 3-D. The achieved location uncertainty was on the order of 1nm and limited by the signal-to-noise ratio of detected events. These uncertainties were corroborated by detections of fracture intersections at the monitoring boreholes. Three intervals of the dedicated injection borehole were hydraulically stimulated by water injection at pressures up to 33nMPa and flow rates up to 5nL/min. We located 1,933 seismic events during several injection periods. The recorded seismicity delineates a complex fracture network comprised of multistrand hydraulic fractures and shear-reactivated, preexisting planes of weakness that grew unilaterally from the point of initiation. We find that heterogeneity of stress dictates the seismic outcome of hydraulic stimulations, even when relying on theoretically well-behaved hydraulic fractures. Once hydraulic fractures intersected boreholes, the boreholes acted as a pressure relief and fracture propagation ceased. In order to create an efficient subsurface heat exchanger, production boreholes should not be drilled before the end of hydraulic stimulations.

Assemblages of fossil plant remains have been widely used to reconstruct past climatic conditions, usually through the application of methods that involve either finding vegetation analogues on the modern landscape (and using the modern associated climatic values as the basis for an estimate) or using the modern climatic ranges of individual taxa in an assemblage to determine the range of a given climate variable that would allow these plant taxa to live together. Although these approaches are relatively straightforward, it is difficult to assess the uncertainties associated with each approach, particularly in regard to their application to plant macrofossil assemblages. To explore the uncertainty that may arise from inaccuracy and imprecision in climate reconstructions and from ecological considerations we used variants of both approaches to estimate climate from two data sets of modern vegetation assemblages from the southwestern United States: (1) 1752 gridded “virtual plant assemblages” based on plant range maps that provide uniform spatial coverage of the presence or absence of major woody plant taxa across the study area; and (2) 43 modern packrat (Neotoma spp.) midden presence-absence assemblages that are similar to fossil midden assemblages. By comparing observed and estimated climate values, we evaluated the quality of the climate estimates, identified sources of uncertainty, and characterized the nature and magnitude of the effects of these uncertainties on the climate estimates. Uncertainties in estimating climate from vegetation assemblages arise because any given plant taxon (or assemblage) must have the resiliency to survive a range of climatic variability, and because of the strong intercorrelations among climatic variables in the modern climate data. Additional sources of uncertainty in climate estimates from plant assemblages include: (1) the modern climate and plant distribution data that are selected as the basis for estimation; (2) the particular quantitative approach that is used to estimate climate; (3) the sufficiency of the number of taxa in the analysis for providing an unbiased representation of the vegetation community as it existed for each time period in the analysis; and, (4) the location of the assemblage on the climatic and environmental gradients in the calibration data set for each climate variable under consideration. We conclude that vegetation assemblages can provide valid and reproducible estimates of climatic variables and that the primary trends and mapped patterns in the observed climate data can be reconstructed from such estimates. However, many factors may affect the quality of an estimate from a given plant assemblage, including aspects of data selection, data adequacy, methodologies, and the location of the assemblage site relative to gradients in the base climate data. It is particularly difficult to accurately estimate extreme values in the observed climate data, because estimated values from either end of an observed climate gradient necessarily “move toward the middle” of the gradient. In addition, the interval chosen to represent modern climate (here we used 1961 to 1990) may have a large impact on the size of the estimated difference between modern and past climate at a given site.

Relative permeability is an important attribute influencing subsurface multiphase flow. Characterization of relative permeability is necessary to support activities such as carbon sequestration, geothermal energy production, and oil and gas exploration. Previous research efforts have largely neglected the relative permeability of wellbore cement used to seal well bores where risks of leak are significant. Therefore this study was performed to evaluate fracturing on permeability and relative permeability of wellbore cement. Studies of relative permeability of water and air were conducted using ordinary Portland cement paste cylinders having fracture networks that exhibited a range of permeability values. The measured relative permeability was compared with three models, 1) Corey-curve, often used for modeling relative permeability in porous media, 2) X-curve, commonly used to represent relative permeability of fractures, and 3) Burdine model based on fitting the Brooks-Corey function to fracture saturation-pressure data inferred from x-ray computed tomography (XCT) derived aperture distribution results. Experimentally-determined aqueous relative permeability was best described by the Burdine model. Though water phase tended to follow the Corey-curve for the simple fracture system while air relative permeability was best described by the X-curve.

One important issue in the storage of large volumes of fluids, mainly water and CO2, in the deep subsurface is to determine the resulting field-scale-induced displacements and consequences of overpressures on the mechanical integrity of the storage reservoir and surroundings. A quantifiable estimation of displacement can be made by combining the robust, cost-effective, and repeatable geophysical techniques of micro-gravimetry, differential global positioning system (DGPS), and differential synthetic aperture radar interferometry (DInSAR). These techniques were field tested and evaluated for the first time on an active large-volume aquifer storage and recovery (ASR) project in Pendleton, Oregon, USA, where three ASR wells are injecting up to 1.9 million m 3 year −1 into basalt aquifers to a depth of about 150 m. Injection and recovery of water at the wells are accompanied by significant gravity anomalies and vertical deformation of the ground surface localized to the immediate surroundings of the injection wells as evidenced by DGPS and gravity measurements collected in 2011. At a larger scale, and between 2011 and 2013, DInSAR monitoring of the Pendleton area shows sub- centimetric deformation in the western part of the city and close to the injection locations associated with ASR cycle. Deformations are found to be temporally out phased with the injection and recovery events due to complex groundwater flow. A numerical simulation of the effect of the water injection gives results in good agreement with the observations and confirms the validity of the approach, which could be deployed in similar geological contexts to look at the mechanical effects of water and gas injections.

In North America, terrestrial records of biodiversity and climate change that span Marine Oxygen Isotope Stage (MIS) 5 are rare. Where found, they provide insight into how the coupling of the ocean–atmosphere system is manifested in biotic and environmental records and how the biosphere responds to climate change. In 2010–2011, construction at Ziegler Reservoir near Snowmass Village, Colorado (USA) revealed a nearly continuous, lacustrine/wetland sedimentary sequence that preserved evidence of past plant communities between ~140 and 55 ka, including all of MIS 5. At an elevation of 2705 m, the Ziegler Reservoir fossil site also contained thousands of well-preserved bones of late Pleistocene megafauna, including mastodons, mammoths, ground sloths, horses, camels, deer, bison, black bear, coyotes, and bighorn sheep. In addition, the site contained more than 26,000 bones from at least 30 species of small animals including salamanders, otters, muskrats, minks, rabbits, beavers, frogs, lizards, snakes, fish, and birds. The combination of macro- and micro-vertebrates, invertebrates, terrestrial and aquatic plant macrofossils, a detailed pollen record, and a robust, directly dated stratigraphic framework shows that high-elevation ecosystems in the Rocky Mountains of Colorado are climatically sensitive and varied dramatically throughout MIS 5.

Ninety plant macrofossil taxa from the Ziegler Reservoir fossil site near Snowmass Village, Colorado, record environmental changes at high elevation (2705 m asl) in the Rocky Mountains during the Last Interglacial Period. Present-day vegetation is aspen forest (Populus tremuloides) intermixed with species of higher (Picea,Abies) and lower (Artemisia,Quercus) elevations. Stratigraphic units 4–13 contain montane forest taxa found near the site today and several species that today generally live at lower elevations within (Abies concolor,Lycopus americanus) and outside Colorado (Najas flexilis). These data suggest near-modern climatic conditions, with slightly warmer summer and winter temperatures. This montane forest period was succeeded by a shorter treeless interval (Unit 14) representing colder and/or drier conditions. In units 15–16, conifer trees reoccur but deciduous and herb taxa are lacking, suggesting a return to warmer conditions, although cooler than during the earlier forest period. Comparison of these inferred paleoclimatic changes with the site's geochronologic framework indicates that the lower interval of sustained warmth correlates with late MIS 6–early 5b (~138–94 ka), the cold interval with MIS 5b (~94–87 ka), and the uppermost cool assemblages with MIS 5a (~87–77 ka).

The objective of this study was to quantify transport of Eu colloids in the vadose zone at the semiarid Hanford site. Eu-hydroxy-carbonate colloids, Eu(OH)(CO3), were applied to the surface of field lysimeters, and migration of the colloids through the sediments was monitored using wick samplers. The lysimeters were exposed to natural precipitation (145-231 mm/year) or artificial irrigation (124-348 mm/year). Wick outflow was analyzed for Eu concentrations, supplemented by electron microscopy and energy-dispersive X-ray analysis. Small amounts of Eu colloids (1%) were detected in the deepest wick sampler (2.14 m depth) 2.5 months after application and cumulative precipitation of only 20 mm. We observed rapid transport of Eu colloids under both natural precipitation and artificial irrigation; that is, the leading edge of the Eu colloids moved at a velocity of 3 cm/day within the first 2 months after application. Episodic infiltration (e.g., Chinook snowmelt events) caused peaks of Eu in the wick outflow. While a fraction of Eu moved consistent with long-term recharge estimates at the site, the main mass of Eu remained in the top 30 cm of the sediments. This study illustrates that, under field conditions, near-surface colloid mobilization and transport occurred in Hanford sediments.

The mutual climatic range (MCR) technique is perhaps the most widely used method for estimating past climatic parameters from fossil assemblages, largely because it can be conducted on a simple list of the taxa present in an assemblage. When applied to plant macrofossil data, this unweighted approach (MCR un ) will frequently identify a large range for a given climatic parameter where the species in an assemblage can theoretically live together. To narrow this range, we devised a new weighted approach (MCR wt ) that employs information from the modern relations between climatic parameters and plant distributions to lessen the influence of the “tails” of the distributions of the climatic data associated with the taxa in an assemblage. To assess the performance of the MCR approaches, we applied them to a set of modern climatic data and plant distributions on a 25-km grid for North America, and compared observed and estimated climatic values for each grid point. In general, MCR wt was superior to MCR un in providing smaller anomalies, less bias, and better correlations between observed and estimated values. However, by the same measures, the results of Modern Analog Technique (MAT) approaches were superior to MCR wt . Although this might be reason to favor MAT approaches, they are based on assumptions that may not be valid for paleoclimatic reconstructions, including that: 1) the absence of a taxon from a fossil sample is meaningful, 2) plant associations were largely unaffected by past changes in either levels of atmospheric carbon dioxide or in the seasonal distributions of solar radiation, and 3) plant associations of the past are adequately represented on the modern landscape. To illustrate the application of these MCR and MAT approaches to paleoclimatic reconstructions, we applied them to a Pleistocene paleobotanical assemblage from the western United States. From our examinations of the estimates of modern and past climates from vegetation assemblages, we conclude that the MCR un technique provides reliable and unbiased estimates of the ranges of possible climatic conditions that can reasonably be associated with these assemblages. The application of MCR wt and MAT approaches can further constrain these estimates and may provide a systematic way to assess uncertainty. The data sets required for MCR analyses in North America are provided in a parallel publication.

A field test of desiccation is being conducted as an element of the deep vadose zone treatability test program. Desiccation technology relies on removal of water from a portion of the subsurface such that the resultant low moisture conditions inhibit downward movement of water and dissolved contaminants. Previously, a field test report (Truex et al. 2012a) was prepared describing the active desiccation portion of the test and initial post-desiccation monitoring data. Additional monitoring data have been collected at the field test site during the post-desiccation period and is reported herein along with interpretation with respect to desiccation performance. This is an interim report including about 2 years of post-desiccation monitoring data.

Desiccation of the vadose zone has the potential to reduce the flux of contaminants to underlying groundwater by removing moisture and decreasing the aqueous-phase permeability of the desiccated zone. However, data to evaluate implementation of desiccation are needed to enable consideration of desiccation as a potential remedy. Implementation of desiccation was field tested by injecting dry nitrogen gas to a target treatment zone and monitoring the spatial and temporal progress of the drying process. Aqueous waste discharges to disposal cribs approximately 50 years ago distributed water and contaminants, including primarily technetium-99 and nitrate, within the 100-m deep vadose zone at the test site. A field test location was selected adjacent to one of the former disposal cribs. The test was conducted in a contaminated portion of the vadose zone dominated by fine sands with lenses of silt material. Desiccation reduced volumetric moisture content to as low as 0.01. The lateral and vertical distribution of drying from the injection well was influenced by the subsurface heterogeneity. However, over time, desiccation occurred in the initially wetter, lower permeability lenses.

[1] We explored the use of continuous waterborne electrical imaging (CWEI), in conjunction with fiber-optic distributed temperature sensor (FO-DTS) monitoring, to improve the conceptual model for uranium transport within the Columbia River corridor at the Hanford 300 Area, Washington. We first inverted resistivity and induced polarization CWEI data sets for distributions of electrical resistivity and polarizability, from which the spatial complexity of the primary hydrogeologic units was reconstructed. Variations in the depth to the interface between the overlying coarse-grained, high-permeability Hanford Formation and the underlying finer-grained, less permeable Ringold Formation, an important contact that limits vertical migration of contaminants, were resolved along ∼3 km of the river corridor centered on the 300 Area. Polarizability images were translated into lithologic images using established relationships between polarizability and surface area normalized to pore volume (Spor). The FO-DTS data recorded along 1.5 km of cable with a 1 m spatial resolution and 5 min sampling interval revealed subreaches showing (1) temperature anomalies (relatively warm in winter and cool in summer) and (2) a strong correlation between temperature and river stage (negative in winter and positive in summer), both indicative of reaches of enhanced surface water–groundwater exchange. The FO-DTS data sets confirm the hydrologic significance of the variability identified in the CWEI and reveal a pattern of highly focused exchange, concentrated at springs where the Hanford Formation is thickest. Our findings illustrate how the combination of CWEI and FO-DTS technologies can characterize surface water–groundwater exchange in a complex, coupled river-aquifer system.

Publisher Summary This chapter explores the strengths and shortcomings of the major sources of data on Quaternary vegetation and climate change and discusses the use of models as a means to explore past and potential future environmental changes. The flora and major vegetation types of the western United States are present for several million years. Ongoing changes in atmospheric chemistry, climate, and human activities may lead to major vegetation changes over the coming decades to centuries. The combination of observations from the paleoenvironmental record, modern ecological studies, and modeling now permit assessments of the magnitude of potential future changes in the context of natural variability. They also provide opportunities for hypothesis testing and identification of the processes driving past changes in vegetation and climate. Understanding the dynamics of paleoenvironmental change can contribute to current conservation and natural resource management efforts and will help conservation and natural resource managers anticipate the potential rate, magnitude, and complexity of future vegetation change.

Soil desiccation was recently field tested as a potential vadose zone remediation technology. Desiccation removes water from the vadose zone and significantly decreases the aqueous-phase permeability of the desiccated zone, thereby decreasing movement of moisture and contaminants. The two- and three-dimensional distribution of moisture content reduction with time provides valuable information for desiccation operations and for determining when treatment goals have been reached. This type of information can be obtained through the use of geophysical methods. Neutron moisture logging, cross-hole electrical resistivity tomography, and cross-hole ground-penetrating radar approaches were evaluated with respect to their ability to provide effective spatial and temporal monitoring of desiccation during a treatability study conducted in the vadose zone of the USDOE Hanford site in the state of Washington.

In 1841, Miss Anning, of Lyme Regis, drew my attention to some black-coloured substances which she had occasionally met with in the interior of the Ammonites Bucklandi, and which she considered to indicate the presence of an ink-bag in the animal of the Ammonite, corresponding to that of the Sepiidae. From these and other specimens, it appeared to me evident that these substances had constituted, not an ink bag, but a laminar appendage to the animal, adapted to discharge some unascertained function. The specimens presented the appearance of a very thin concave shell, glossy on its outer surface, with irregular concentric undulations, crossed by longitudinal striae and fine irregular oblique wrinkles. In the middle of the external margin is a large undulation or sinus. The inner surface, as exhibited by its cast, is of a dull black, the outer surface of the shell being of the colour of horn. Miss Anning informed me that these bodies generally occur about the middle of the outer chamber of the ammonite, whence they are obtained by breaking the fossil; but as this process more frequently destroyed than exposed the object of search, I was unable, during my stay at Lyme Regis, to procure any tolerably perfect specimens, or to arrive at any satisfactory conclusion as to their nature.

So laboriously minute have been the researches of the Officers of the Geological Survey of Great Britain, that it is only where some fresh sections have been subsequently exposed by the operations of nature or of man that any material additions or corrections of that Survey can be looked for. A case of the kind has lately occurred in Herefordshire, revealing a small protrusion of Silurian rocks in the midst of the Old Red Sandstone, and accompanied by circumstances of some geological interest. A quarry having been opened near the base of the Old Red Sandstone, a few hundred yards west of Hagley House, near Lugwardine, and a deep drain having been cut from the quarry towards the S.E., the junction-beds of the Old Red Sandstone and of the Upper Ludlow Rock were unexpectedly exposed. This circumstance attracted the notice of M. J. Scobie, Esq., of Hereford, to whom I am indebted for having my attention drawn to the spot, and for many interesting organic remains and geological details which his residence in the vicinity enabled him to collect. I must also express my obligations, and those of the other geological friends who accompanied me, to Robert Biddulph Phillipps, Esq., the owner of the land, who kindly caused part of the quarry to be re-opened for our inspection.

The tertiary deposit here described occupies a considerable portion of the peninsula of Lixouri, on the western side of the Gulf of Argostoli. It forms a series of ridges, extending for two or three miles to the north and south of the village of Lixouri, and running parallel to the strike of the secondary rocks of the island of Cephalonia, as well as of the whole of the Ionian isles, which conform in their directions to the great mountain systems of the Apennines and of Dalmatia. The beds slope gradually to the eastward, and present a succession of steep escarpments towards the west. The width of this tertiary zone may be about four miles from the sea on the east to the mountainous ridge of secondary rocks against which they rest on the west. The beds are all perfectly conformable, dipping a few degrees to the north of east by compass, at an angle of from 45° to 55°. Their aggregate thickness may be estimated at about 900 feet. They are remarkable for the great number and variety of fossils which they contain, some of the beds being almost wholly composed of shells, in the most perfect state of preservation, many of which belong to species now existing in the Mediterranean. A large proportion of these shells are identical with species figured by Brocchi from the Subapennine beds, indicating that this deposit must be referred to the Pliocene epoch. This locality is also interesting from the great thickness of the

In a paper read to this Society in June last* I noticed the occurrence at Hagley, four miles N.E. of Hereford, of that remarkable deposit the “Ludlow Bone Bed,” a stratum interesting not only for its wide extension, as contrasted with its very slight vertical thickness, but also as presenting nearly, if not quite, the earliest known indication of Vertebrate Life on the surface of our Planet. I showed its close conformity, at Hagley, to the type of the same deposit as first described by Sir R. Murchison near Ludlow (‘Silurian System,’ p. 198), and enumerated certain Fish and Mollusca which it there contained. I also briefly referred to certain seed-like bodies which seemed to indicate the commencement, or at least the first appearance, of terrestrial vegetation. The interest of the subject has since induced me to trace out the same deposit at various points towards the S.E. Prof. Phillips had already indicated the existence of Ichthyic fragments near the boundary-line of the Silurian and Devonian systems at two or three points in this direction (Mem. Geol. Surv. vol. ii. pp. 178, 191), but had not gone into much detail as to their structural character. Having succeeded in tracing this stratum at additional localities, and having obtained in it some fossil remains of considerable interest, it seemed desirable to communicate these rules to the Society. It will be remembered that at Hagley the Ludlow Bone-bed occurs as a thin stratum of fish bones, scales and coprolites, mixed with carbonaceous fragments

Preface. In former communications to the Geological Society*, the System of the New Red Sandstone of Gloucestershire, Worcestershire, and Shropshire was subdivided by Mr. Murchison in the following manner: | | Foreign Equivalents. | |:---------------------------------------------------------- | -------------------------------- | | 1. Marls with salt, gypsum, and a thin course of sandstone | Keuper — Marnes Irisees. | | 2. Quartzose red sandstone, and conglomerate | Bunter Sandstein — Gres Bigarre. | | 3. Calcareous conglomerate=magnesian limestone | Zechstein. | | 4. Lower new red sandstone | Rohe-Todte-Liegende. | The objects of this Memoir are to describe with greater precision than had been previously attempted, the two superior members of this group, by showing that they are both fossiliferous, and that they can be separated from each other by their zoological and lithological characters, as well as by geological position. The communication is the result of a joint examination of the district, and of other observations made independently by the authors. In it, they propose to describe the prominent characters of the two superior formations of the New Red System as exhibited in Gloucestershire and Worcestershire, and to extend their remarks concerning those beds into Warwickshire. The strata will be considered in descending order. § 1. Saliferous Marls and Sandstone (For, Syn. Keuper—Marnes Irtsees.). Having examined the junction-beds between the lias and the new red sandstone from the southern extremity of Gloucestershire through Worcestershire into Warwickshire, we have only to repeat what was adduced by one of us on previous occasions, that in many positions the lowest calcareous band or “limestone of the lower lias shale” is also underlaid by shale, which

The well-known promontory of the Cotswolds, called Leckhampton Hill, affords probably the best locality in Gloucestershire for studying the relative position of the various beds of the inferior oolite and subjacent lias. From its great height and steepness, the entire series of the oolite is admirably exposed to view, and the extensive quarries from which Cheltenham has been mainly built, afford every facility for examining the formation. The geologists of Cheltenham and the neighbourhood are well acquainted practically with the subdivisions of the strata and their organic contents, but no exact definitions or precise measurements of these strata have, I believe, ever yet been made. Mr. Buckman9s ‘Chart’ contains a section of Leckhampton Hill, and is valuable for its descriptions of the mineral character and organic remains of some of the beds. But it does not attempt to exhibit all the subdivisions of the oolite, or to show their absolute and relative thicknesses. It appeared therefore desirable that a more elaborate survey should be made, and with this object I gladly availed myself of the aid of the Rev. A. D. Stacpoole of Oxford, whose skill in the use of surveying instruments was of great service. Where the strata were exposed in a vertical escarpment and were accessible, they were accurately measured, but in other cases their thickness could only be ascertained by means of the sextant. By putting together the varied observations thus obtained, we constructed the section given at p. 242, supra . It is drawn on a uniform

I AM desirous of calling the attention of the Society to some remarkable dikes which penetrate lias schist at Ethie, near Cromarty. The beds of lias at this place have been described by Mr. Murchison in our Transactions*, and their relations are given in the accompanying wood-cut (p. 600). These beds are only exposed at low water, and dip towards the sea at an angle which gradually increases in approaching high-water mark, where they become perpendicular. Cliffs of gneiss and red conglomerate rise immediately from the shore, but the broken fragments which are scattered near high-water mark, conceal the actual junction of the lias with these older rocks. The dikes, which are here seen to penetrate the lias, are remarkable for their mineral character, which so precisely resembles that of certain altered quartzose sandstones, that it is impossible to refer them to a purely igneous origin. The substance of which they are composed, is intensely hard. On examining it with a lens, its component particles are distinctly seen, and bear the closest resemblance to ordinary water-worn grains of sand. The stone is penetrated by carbonate of lime, which produces a slight effervesence on the application of an acid; and it has assumed a pseudo-crystalline structure, which exhibits, when held in certain lights, the peculiar lustre of the calcareous sandstones of Fontainebleau and other places. A careful examination of the locality sufficed to show, that however much this rock might resemble an aqueous product, yet that it forms genuine intrusive dikes

The shells of the microscopic order Foraminifera , which occur so abundantly in the cretaceous and tertiary series, are found much more rarely as we descend through the secondary formations. Examples of them have indeed occurred both in the oolitic and the palaeozoic series, but I believe that these fossils have not hitherto been met with in the lias. The Rev. P.B. Brodie, while pursuing his interesting and successful researches into the fossil insects of the lower lias, was the first to discover these minute objects. In a bed of yellowish shaly stone, a few feet above the ‘insect limestone’ of wainlode cliff, Gloucesrtershire, he detected small white dots about 1/50th of an inch in diameter, which when examined by a powerful microscope prove to discoid spiral shells, apparently unattached, with five to six smooth, rounded, narrow volutions, devoid of striations or any other distinctive characters. As there are no traces of concamerations, we perhaps ought to refer them to the serpulidae rather than the Foraminifera , although their extreme minuteness would point to be latter family as a more probable clue to their affinities. It has been suggested to me that their characters resemble those of the genus Orbis of Lea, and I will therefore denominate the fossil provisionally Orbis infimus (see figure a). These fossils also occur ina similar bed of shaly limestone near the base of the lias at Cleeve Bank, between Evesham and Bidford. Along with them I here obtained one specimen of an equally minute fossil, which