An apparatus for consolidating fine grained materials under controlled conditions of total stress, pore fluid pressure and temperature is described and the variation in chemistry of pore fluid expelled during compaction from a montmorillonitic material at 40°C is reported. The decrease in concentration of dissolved salts in the pore fluid is related exponentially to the effective axial pressure.

Biotite in deeply weathered granitic rocks in southwestern Australia has altered to exfoliated grains composed of biotite, mixed-layer clay minerals, kaolinite, vermiculite, gibbsite, goethite, and hematite. Discrete vermiculite and vermiculite-dominant mixed-layer clay minerals are not major weathering products. Oxidation of octahedral iron in biotite is associated with ejection of octahedral cations, loss of interlayer K, and a contraction of the b-dimension of the biotite sheet. Si, Mg, Ca, Mn, K, and Na are lost from biotite during weathering, and Ti, Al, Ni, and Cr are retained. Fe and water have been added to the grains during weathering. Much Fe occurs as aggregates of microcystalline, aluminum-rich goethite particles on flake surfaces and within etchpits, with smaller amounts occurring as hexagonal arrangements of lath-shaped crystals of goethite on flake surfaces.

The composition of clay mineral suites derived from Triassic argillite and shale were compared with those of the consolidated parent sediments. Lockatong argillite, near the weathered zone, is composed mainly of illite, chlorite, and feldspar. In the clay horizon immediately above it, illite replaces the feldspar and kaolinite increases with distance from the contact until, near the top of the weathered zone, it is almost the only clay mineral present. A similar study was carried out on Brunswick shale. Here the parent rock consists mainly of illite, and some kaolinite, montmorrilonite, quartz, and feldspar. The kaolinite increases gradually as one progresses upward through the weathered zone, montmorillonite decreases, but approximately 30 per cent illite is still found in the top layers. Chlorite in the argillite near the weathered zone is randomly oriented while illite shows strong preferred orientation, probably indicating that chlorite formed in place during weathering. Illite in the Brunswick shale shows strong preferred orientation.

These two Triassic sediments are less than 5 miles apart and one may assume that they had a similar post-depositional environment. The difference in diagenetic development is striking and must be attributed mainly to the chemical composition and lithology of the parent sediment.

The orientation of clay particles in the solid rock was studied with the aid of an X-ray diffraction technique based on the analysis of cylindrical samples. Three-dimensional intensity data thus obtained were presented by vectors whose ends form a surface which is characteristic of the orientation of the particles. Generally the vectors generate hemispherical normal distributions whose principal vector coincides with the normal to the bedding plane.

To identify mineral alterations which might occur in stream environments, predominantly illitic soil clays were equilibrated in bottom sediment environments under natural and laboratory conditions for 217 and 98 days, respectively. Changes occurring after 217 days on the bottom of the Auglaize River, Ohio, consisted of a reduction in carbonate content, a decrease in particle size, and a slight loss of Al and Si; however, no significant changes in basal spacings were observed.

Clays equilibrated in river water under laboratory conditions at 4° and 25°C in CO2, N2, or air atmospheres showed only an increase in oxalate-extractable iron. The concentrations of Al, Si, Fe, Mn, K, and Ca in solution above the clays varied with the atmosphere and temperature. The concentrations of Fe, Al, and Si in solution may have been influenced by the dissolution of amorphous Al-Fe-Si compounds. Therefore, the mineralogical differences between soils in the watershed and sediments in the drainage system can not be attributed to mineralogical transformations during residence in the drainage system.

The scanning electron microscope (SEM) is useful in the identification of biogenic opal. Opaline spheres, cups, and scrolled or convoluted sheets were identified in both soil and vegetative isolates. X-ray diffraction analysis indicates that both alpha quartz and cristobalite were co-associated with the amorphous opaline phase synthesized during life metabolism of deciduous tree leaves. Such crystalline phases were most abundant in the 2–5 μm fraction and many consist of anitsotropic rods with parallel extinction or equidimensional bodies with aggregate extinction. Between 2/3 and 3/4 of the total opal isolate from deciduous tree leaves was solubilized when digested for 2–5-min in boiling 0.5 N NaOH. Rate of dissolution was a function of particle-size and tree species. Biogenic opal of forest origin was about 10–15 times more soluble than grass opal, which probably reflects the higher specific surface of the former.

The hydrated form of tubular halloysite [halloysite (10 Å)] was observed by a conventional electron microscope equipped with an environmental cell (E.C.), by which the “natural” form was revealed without dehydration of the interlayer water. This study mainly reports the selected area electron diffraction (SAED) analysis of the halloysite (10 Å) and its morphological changes by dehydration. The SAED pattern showed halloysite (10 Å) has two-layer periodicity in a monoclinic structure with the unit cell parameters of a = 5.14 Å, b = 8.90 Å, c = 20.7 Å, β = 99.7°, in space group Cc, and almost the same structure as the dehydrated form of halloysite [halloysite (7 Å)]. This means that the dehydration of the interlayer water did not greatly change or affect the structure of halloysite (10 Å). Accompanying the dehydration of the interlayer water, there appeared along the halloysite tube axis clear stripes that were about 50–100 Å in width. The diameters of the tubular particles also increased about 10%. From the results of various experiments, such as a focussing series, observation of the surface structure by the replica method, observation of end-views of the tubular particles, and others, these two phenomena were explained as follows: Halloysite crystals have “domains” along the c-axis direction, the thicknesses of the “domains” vary ca. 50–100 Å. They are tightly connected with each other when the halloysite is hydrated, but are separated from each other by the dehydration of the interlayer water, whereupon the stripes come into existence along the tube axis. Taking these considerations into account, a model of dehydration is proposed. Moreover, a new method of calculating the β-angle is proposed in the Appendix.

Halloysite (metahalloysite) of various particle sizes has been altered with oxalic and EDTA acids, at room temperature and during different periods of time (5–90 days). The oxalic acid attack at first achieved only a recrystallization of halloysite. The recrystallization is much more significant the smaller the size of the treated halloysite particles. Later the material is destroyed. The EDTA treatment also has provoked during the first days a recrystallization of the halloysitic material which is destroyed again after about 20–25 days. Later kaolinite is formed. The kinetic curve of kaolinite formation is symmetrical with respect to that corresponding to the diminution of amorphous material in the sample. The influence of the halloysite particle size and the complexing effect of the acids in relation to the resulting products are discussed.

High resolution electron micrographic techniques have been employed for surveying the size and shape distributions of kaolinite particles, both plates and stacks, from well-crystallized Georgia deposits.

Both size and shape follow typical, positively-skewed, frequency distributions. Particle thicknesses among plates appear quantized, dominantly as hoxalaminae and subordinately as trilaminae of the basic c-axis dimension in the unit cell. Specimens subjected to severe shear and attrition show intermediate values of thickness, i.e. 3n + 1 and 3n + 2. Profile studies on kaolinite stacks reval integral platelet units whose distribution in thickness corresponds to that of individual plates.

Energy calculations for fracture (cleavage ‖ to c-axis) and delamination (cleavage ⊥c-axis) processes indicate that hydrokinetic cleavage in nature should result in particles having an aspect ratio distribution peaking near 6: 1. The dominance of stacks above 10 μ is suggestive of in situ weathering. Experimental shear measurements correlate well with these proposals.

Sedimentation studies with clays of various shapes and distributions were performed in a variety of aqueous media, including sea water. Sediment volume data, microscopic observations, and theoretical packing calculations are compared with the several mechanisms proposed for plate-stack genesis.

Identifying the absence of situation awareness (SA) in air traffic controllers is critical since it directly affects their hazard perception. This study aims to introduce and validate a multimodal methodology employing electroencephalogram (EEG) and eye-tracking to investigate SA variation within specific air traffic control contexts. Data from 28 participants executing the experiment involving three different SA-probe tests illustrated the conceptual relationship between EEG and eye-tracking indicators and SA variations, using behavioural data as a proxy. The results indicated that both EEG and eye-tracking metrics correlated positively with the SA levels required, that is, the frequency spectrum in the β (13–30 Hz) and γ (30–50 Hz) bands, alongside the fixation/saccade-based indicators and pupil dilation increased in response to higher SA levels. This research has substantial implications for investigating SA using a human-centric approach via psychophysiological indicators, revealing the intrinsic interactions between the human capability envelope and SA, contributing to the development of a real-time monitoring system of SA variations for air transportation safety research.

The present paper presents the mineralogical composition of sediments from the Spanish Wealdian facies, selected from four stratigraphic sections of several regions in the Southern Cordillera Iberica.

Three of these sections show an irregular alternation of kaolinite rich sandy and silty-clay beds. The fourth section which contains calcareous layers, is very important from a geological point of view, because it is located where the structures of two ranges, the Iberian and the Betics, converge.

The clays of about 80 samples from these sections always consist of illite, kaolinite and interstratified clay minerals. The sandy layers also contain quartz, as well as potash and calcic-sodic felspars. The fine fraction (< 2 µm) is composed of kaolinte, between pM and T types, swelling illite and randomly interstratified clay minerals of the type (10I-14M), richer in 10 Å layers.

From the mineralogical and crystalchemical data and field observations, it is deduced that these sediments are mainly detrital. This and the layer alternation suggest, for the Upper Jurasic and Lower Cretaceous (Wealdian facies), a climate alternating from biostatic to rhexistatic. Alternating laterization and erosion might supply the materials to the Wealdian sedimentary basin.

The conditions under which an exchanger phase will behave as an ideal mixture are established from thermodynamic principles. It is shown that, if a stoichiometric cation-exchange reaction is reversible, the exchanger phase will exhibit ideal behavior if the Vanselow selectivity coefficient is independent of the exchanger composition. This criterion is applied to some recently published data for Na+-trace metal cation exchange on Camp Berteau montmorillonite. An analysis of the data suggests that, so long as the exchange process is reversible, Na+-trace metal cation exchange produces an exchanger phase that behaves as an ideal mixture.

Glauconite-smectite and illite-smectite interlayered minerals are compared by various means in an attempt to establish the mineralogical relations between the two groups. Experiments at 2 Kb pressure and 200–350°C are reported as well as microprobe scans of pelletal glauconites. This new information is used along with published chemical data in order to establish that

(1) Illite and glauconite mixed layered phases appear to be crystallographically similar. Both series show the same relations between potassium (mica) content and the amount of smectite layers apparent in the interlayered structure.

(2) Illite and glauconite mica or mica-like phases can be separated on the basis of Fe and K contents.

(3) Probable phase relations of the two mixed layered mineral series indicate that, when the starting materials contain mixed layered mica-smectites, increasing temperature produces an iron-rich mica in the case of glauconite and an aluminous mica in the case of illite. The mixed layered phases present at intermediate temperatures are not the same for illites and glauconites.

Apparently there is no mineralogical or chemical continuity between illite and glauconite when the potassium content is 6 wt % or greater. It might be possible that the potassic interlayered minerals near montmorillonite or nontronite could form a continuous solid solution.

Heats of compression of glass bead-water and clay-water mixtures were determined from the peak heights of the thermograms produced when these mixtures were subjected to pressure in a Calvet differential microcalorimeter. It is known that the heat of compression is directly proportional to the peak height. When the latter quantity was plotted against the pressure applied to any mixture, two intersecting straight lines were obtained. The change in slope at the point of intersection was interpreted as being the result of a pressure-induced higher-order phase transition in the water.

The differential peak height, ε, was defined as the rate of change of peak height with pressure/g of water present in the mixture. Hence, it is directly proportional to the rate of change of the heat of compression with pressure/g of water. Values of ε were determined for both glass bead-water and clay-water mixtures containing different proportions of solids. It was found that ε remained nearly constant with increasing proportions of glass beads, whereas, it varied in a non-uniform way with increasing proportions of clay. Also, its values in the clay-water mixtures were relatively high. Calculations showed that the difference in ε values for the two mixtures could not be ascribed to the exchangeable cations associated with the clay particles. Consequently, it was ascribed to the effect of the particle surfaces on the structure of the vicinal water.

Consecutive squares are, of course, not equally spaced: the gap increases by 2 each time. However, it is quite possible to select three equally spaced squares, for example 1, 25, 49. Actually, such triples correspond to Pythagorean triples in a pleasantly simple way, which we will describe.

Clay mineral associations in saprolite of two andesites from the Cascade Range of northeastern California were determined. Sesquioxidic allophane with a high CEC delta value dominates the clay fraction of the least weathered saprolite in each series (47% and 37% in hypersthene andesite and olivine andesite saprolites, respectively). With further weathering, the content of amorphous clay remains high (over 30% in all cases) but the CEC delta value of the clay drops markedly. The amorphous material in the more weathered saprolite has the properties of halloysitic allophane. Halloysite, present in all saprolites, is highest in concentration (over 30%) in the more strongly weathered members of each of the saprolite series. Formation of sesquioxidic allophane during early stages of weathering and its transformation to halloysitic allophane and halloysite during later stages of weathering are supported by X-ray diffraction, electron microscopic, DTA, elemental analysis, and CEC delta value data.

Cretaceous bentonites were collected in outcrop from the Sweetgrass Arch and the Disturbed Belt in Montana. The mixed-layer illite-smectite (I/S) components of the bentonites from the Sweetgrass Arch have from 0 to 25% illite layers and no detectable structurai Fe2+, whereas the samples from the Disturbed Belt have from about 25 to 90% illite layers, and all contain Fe2+. A positive correlation (r = 0.89) exists between the percentage of structural iron that is Fe2+ and the amount of fixed interlayer K in the I/S.

The higher percentage of illite layers in the samples from the Disturbed Belt is attributed to reactions related to elevated temperatures caused by burial beneath thrust sheets. The increase in Fe2+/Fe3+ with increasing percentages of illite layers is tentatively attributed to a redox reaction involving the oxidation of organic matter. Although there is no statistical evidence for an increase in octahedral charge with an increase in illite layers when all the samples are considered together, iron reduction may have contributed as much as 10 to 30% of the increase in total structural charge that occurred in any given sample during metamorphism. The remaining structural charge increase can be attributed to the substitution of Al3+ for Si4+ in the tetrahedral sites.