Silicate Blocks Research Articles

Preparation of calcium silicates with long-fiber (needle) particles

The results of our experimental studies of processes for the synthesis of calcium silicate and hydrosilicate powders with needle-shaped particles from phosphogypsum (technogenic calcium-containing raw material) and sodium silicate block (silicon-containing product of chemical industry) under hydrothermal and microwave-hydrothermal conditions are presented.

Cheirolepidiaceous diversity: An anatomically preserved pollen cone from the Lower Jurassic of southern Victoria Land, Antarctica

To date, the vast majority of fossils described for the extinct conifer family, the Cheirolepidiaceae, have been reported from compression/impressions primarily from Cretaceous rocks; there are fewer reports from permineralizations and the Jurassic. New specimens have recently been discovered in siliceous blocks composed of fusainized layers of plant remains that alternate with fine-grained sediments from the Carapace Nunatak (Lower Jurassic) locality of southern Victoria Land, Antarctica. Specimens were prepared using standard serial cellulose-acetate peel technique, transmitted-light microscopy, and SEM analysis. The cones are ellipsoidal, up to 5.5mm long, and consist of helically arranged microsporophylls, each with a slender stalk containing a single vascular bundle; the distal lamina is peltate and most closely resembles those of the Classostrobus. Four to seven pollen sacs are arranged in an annular cluster abaxial to the sporophyll stalk. In situ Classopollis pollen ranges from 18 to 60μm in equatorial diameter with an average diameter of 30μm. In addition to these well-preserved pollen cones there is a large diversity of vegetative conifer remains within the Carapace Nunatak material including leaf and stem fragments. The discovery of the pollen cones in combination with vegetative remains provides additional information on the reproductive biology of the Cheirolepidiaceae and increases the probability of developing a whole-plant concept for this Jurassic permineralized conifer.

FROM STRUCTURE TOPOLOGY TO CHEMICAL COMPOSITION. XVIII. TITANIUM SILICATES: REVISION OF THE CRYSTAL STRUCTURE AND CHEMICAL FORMULA OF BETALOMONOSOVITE, A GROUP-IV TS-BLOCK MINERAL FROM THE LOVOZERO ALKALINE MASSIF, KOLA PENINSULA, RUSSIA

The crystal structure of betalomonosovite, ideally Na 6 □ 4 Ti 4 (Si 2 O 7 ) 2 [PO 3 (OH)][PO 2 (OH) 2 ]O 2 (OF), a 5.3331(7), b 14.172(2), c 14.509(2) A, α 103.174(2), β 96.320(2), γ 90.278(2)°, V 1060.7(4) A 3 , from the Lovozero alkaline massif, Kola peninsula, Russia, has been refined in the space group P 1 ¯ to R = 6.64% using 3379 observed ( F o > 4σ F ) reflections collected with a single-crystal APEX II ULTRA three-circle diffractometer with a rotating-anode generator (Mo K α), multilayer optics, and an APEX-II 4K CCD detector. Electron-microprobe analysis gave the empirical formula (Na 5.39 Ca 0.36 Mn 0.04 Mg 0.01 ) Σ5.80 (Ti 2.77 Nb 0.48 Mg 0.29 Fe 3+ 0.23 Mn 0.20 Zr 0.02 Ta 0.01 ) Σ4 (Si 2.06 O 7 ) 2 [P 1.98 O 5 (OH) 3 ]O 2 [O 0.82 F 0.65 (OH) 0.53 ] Σ2 , D calc. = 2.969 g cm −3 , Z = 2, calculated on the basis of 26 (O + F) apfu , with H 2 O determined from structure refinement. The crystal structure of betalomonosovite is characterized by extensive cation and anion disorder: more than 50% of cation sites are partly occupied. The crystal structure of betalomonosovite is a combination of a titanium silicate (TS) block and an intermediate ( I ) block. The TS block consists of HOH sheets (H-heteropolyhedral, O-octahedral) and exhibits linkage and stereochemistry typical for Group IV (Ti + Mg + Mn = 4 apfu ) of the TS-block minerals. The I block is a framework of Na polyhedra and P tetrahedra which ideally gives {Na 2 □ 4 [PO 3 (OH)][PO 2 (OH) 2 ]} pfu . Betalomonosovite is an Na-poor OH-bearing analogue of lomonosovite, Na 10 Ti 4 (Si 2 O 7 ) 2 (PO 4 ) 2 O 4 . In the betalomonosovite structure, there is less Na in the I block and in the TS block when compared to the lomonosovite structure. The OH groups occur mainly in the I block where they coordinate P and Na atoms and in the O sheet of the TS block (minor). The presence of OH groups in the I block and in the TS block is supported by IR spectroscopy and bond-valence calculations on anions. High-resolution TEM of lomonosovite shows the presence of pervasive microstructural intergrowths, accounting for the presence of signals from H 2 O in the infrared spectrum of anhydrous lomonosovite. More extensive lamellae in betalomonosovite suggest a topotactic reaction from lomonosovite to betalomonosovite.

Ordovician radiolarians from the Yinisala ophiolitic mélange and their significance in western Junggar, Xinjiang, NW China

The Yinisala ophiolitic melange is located in the southern part of the Xiemisitai Mountains in western Junggar (NW China), and is composed of mafic-ultra mafic rocks, siliceous blocks, marble (marbleized limestone) and pyroclastic rocks, which all crop out as faulted blocks. Rich radiolarian and sponge spicule fossils are found in the siliceous rock for the first time. There are six genera of radiolarians (including one gen. et sp. Indet.) belonging to two families: Inaniguttid gen. et sp. Indet., Inanigutta sp., Inanibigutta sp., Inanihella bakanasensis (Nazarov), Triplococcus acanthicus (Danelian and Popov), Antygopora sp., which are identified to be of late Early to Middle Ordovician age, representing the upper limit of the formation age of the Yinisala ophiolite melange. The ophiolites were developed in the Early Cambrian-Middle Ordovician oceanic environment, probably an important part of the early Paleozoic Paleo-Asian Ocean, based on the composition and structure of the siliceous rock and associated deep-water fossils. The Yinisala, Taerbahatai, and Hongguleleng ophiolitic melange belts can be correlated as a suite of unified subduction accretionary complex, which extends eastward to the eastern Junggar. We consider that there existed an ancient ocean connecting the east and west of northern Junggar in the Early Cambrian-Middle Ordovician.

ANALYSIS OF ENERGY DEMAND FOR LOW-ENERGY MULTI-DWELLING BUILDINGS OF DIFFERENT CONFIGURATION / SKIRTINGOS KONFIGŪRACIJOS MAŽAENERGIŲ DAUGIABUČIŲ PASTATŲ ENERGIJOS POREIKIŲ TYRIMAS

To meet the goals established by Directive 2010/31/EU of the European Parliament and of the Council on the energy performance of buildings, the topics of energy efficiency in new and old buildings must be solved. Research and development of new energy solutions and technology are necessary for increasing energy performance of buildings. Three low-energy multi-dwelling buildings have been modelled and analyzed in the presented study. All multi-dwelling houses are made of similar single-family house cells. However, multi-dwelling buildings are of different geometry, flat number and height. DesignBuilder software was used for simulating and determining heating, cooling and electricity demand for buildings. Three different materials (silicate, ceramic and clay concrete blocks) as bearing constructions of external walls have been analyzed. To decrease cooling demand for buildings, the possibility of mounting internal or external louvers has been considered. Primary energy savings for multi-dwelling buildings using passive solar measures have been determined. Norint pasiekti Europos Sąjungos direktyvos 2010/31/EB tikslus dėl pastatų energinio naudingumo, reikia spręsti energijos efektyvumo klausimus naujų ir esamų pastatų srityje. Naujų energinių sprendinių ir technologijų tyrimai bei plėtra būtini norint padidinti pastatų energinį naudingumą. Šiame tyrime modeliuojami ir analizuojami trys mažaenergiai daugiabučiai pastatai. Visi jie sudaryti iš vienodo dydžio butų, tačiau pastatai tarpusavyje skiriasi geometrija, butų skaičiumi ir aukštingumu. Siekiant nustatyti ir išnagrinėti pastatų šilumos, vėsos ir elektros energijos poreikius, naudotasi DesignBuilder programa. Visų daugiabučių pastatų atvejais nagrinėjamos trys skirtingos išorės sienų laikančiųjų konstrukcijų medžiagos: silikatiniai, keraminiai ir keramzitbetonio blokeliai. Siekiant sumažinti vėsos poreikį pastatuose taip pat buvo analizuojama galimybė sumontuoti vidines arba išorines žaliuzes. Nustatyti sutaupytieji pirminės energijos kiekiai daugiabučių pastatų atvejams taikant pasyviąsias apsaugos nuo saulės priemones.

Late Paleozoic Radiolaria from the Upper Triassic sedimentary mélange in Shangrila, Southwest China and its geological significance

Moderately well-preserved radiolarians were collected recently from the exotic siliceous blocks within the sedimentary mélange of the Upper Triassic Hagong Formation exposed in Shangrila, southwestern China. These radiolarians, characterized by high diversity, include spumellarians, entactinarians, latentifistularians, and albaillellarians. Among them, 28 species of Albaillellaria belonging to 3 genera are taxonomically analyzed. Most species recorded are correlated with coeval radiolarian assemblages from Germany and Japan. Thirteen albaillellarian assemblages are discriminated, ranging in age from Early Carboniferous to Middle Permian. Because the siliceous blocks within the sedimentary mélange originated in the Garze-Litang tectonic belt, the successful recovery of the well-preserved datable albaillellarians provides the age constraints necessary for the interpretation of the tectonic development of the Garze-Litang tectonic belt. On the basis of the deep-water settings indicated by the albaillellarian fauna, we suggest that the sedimentary basin, represented by the Garze-Litang tectonic belt, became a deep-water basin during Early Carboniferous to Middle Permian and, hence, the Dege-Zhongdian microplate must have been gradually separated by rifting from the Yangtze Plate before the Early Carboniferous.

Mūrinių Konstrukcijų Garso Izoliavimas Papildomais Lanksčiais Sluoksniais

For the purposes of accumulating knowledge of how to comply with requirements for new buildings of obligatory sound class C or enhanced acoustic comfort sound classes A and B (Lithuanian Building Technical regulations STR 2.01.07:2003), the article discusses improvement on airborne sound insulation of partitions between dwellings using additional plasterboard layers. The results of an empirical approach were obtained performing in situ measurements of the partitions of masonry from silicate blocks and expanded-clay concrete blocks. Theoretical calculations without the evaluation of flanking paths are added. The paper looks at the peculiarities of in situ measurement methods and the estimation of the limiting uncertainty of the sound reduction index. It is showed that the values of the in situ measurements of the airborne sound reduction index in accordance with requirements EN ISO 140 and EN ISO 717 series for rooms having volume higher than 50 m3 varies depending on frequency range. It has been stated, that improvement on the weighed airborne sound reduction index in the frequency range from 100 Hz to 3150 Hz depends on the properties of additional layers and on the characteristics of the main constructions. Resonance in the low frequency range arising due to additional layers may reduce the weighed airborne sound reduction index defined in the frequency range from 50 Hz to 3150 Hz. This fact must be taken into account when designing improvement on masonry wall insulation using an additional layer in dwellings.

From structure topology to chemical composition. IX. Titanium silicates: revision of the crystal chemistry of lomonosovite and murmanite, Group-IV minerals

AbstractThe crystal structures of lomonosovite, ideally Na10Ti4(Si2O7)2(PO4)2 O4, a = 5.4170(7) Å, b = 7.1190(9) Å, c = 14.487(2) Å, a = 99.957(3)°, β = 96.711(3)°, γ = 90.360(3)°, V= 546.28(4) Å3, Dcalc. = 3.175 g cm“3, and murmanite, ideally Na4Ti4(Si2O7)2O4(H2O)4, a = 5.3875(6) Å, b = 7.0579(7) Å, c = 12.176(1) Å, a = 93.511(2)°, 0 = 107.943(4)°, y = 90.093(2)°, V = 439.55(2) Å3, Dcalc. = 2.956 g.cm∼3, from the Lovozero alkaline massif, Kola Peninsula, Russia, have been refined in the space group P1̄ (Z = 1) to R values of 2.64 and 4.47%, respectively, using 4572 and 2222 observed |F°≥ 4σF| reflections collected with a single-crystal Bruker AXS SMART APEX diffractometer with a CCD detector and Mo-Kα. radiation. Electron microprobe analysis gave empirical formulae for lomonosovite (Na9.50Mn0.16Ca0.11)Σ9.77(Ti4+2.83Nb0.51Mn0.272+Zr0.11Mg0.11Fe2+0.10Fe3+0.06Ta0.01)Σ4.00(Si2.02O7)2(P0.98O4)2(O3.50F0.50)Σ4, Z = 1, calculated on the basis of 22(O+F) a.p.f.u., with H2O determined from structure refinement and Fe3+/(Fe2++Fe3+) ratios obtained by Mössbauer spectroscopy. The crystal structures of lomonosovite and murmanite are a combination of a titanium silicate (TS) block and an intermediate (I) block. The TS block consists of HOH sheets (H-heteropolyhedral, O-octahedral), and is characterized by a planar cell based on translation vectors, t1 and t2, with t1\ ∼5.5 and t2 ∼7 Å and ttA t2 close to 90°. The TS block exhibits linkage and stereochemistry typical for Group IV (Ti = 4 a.p.f.u.) of the Ti disilicate minerals: two H sheets connect to the O sheet such that two (Si2O7) groups link to Ti polyhedra of the O sheet adjacent along tx. In murmanite and lomonosovite, the invariant part of the TS block is of composition Na4Ti4(Si2O7)2O4. There is no evidence of vacancy-dominant cation sites or (OH) groups in the O sheet of lomonosovite or murmanite. In lomonosovite, the I block is a framework of Na polyhedra and P tetrahedra which gives 2[Na3 (PO)4] p.f.u. In murmanite, there are four (H2O) groups in the intermediate space between TS blocks. In lomonosovite, TS and I blocks alternate along c. In murmanite, TS blocks are connected via hydrogen bonding. The H atoms were located and details of the hydrogen bonding are discussed.

The sulfur flow fields of the Fossa di Vulcano

Sulfur flow deposits at the Fossa di Vulcano fumarole field (Italy) are dominated by thermal erosion features. These are characteristic of sulfur flows at this location, where most flows are emplaced in a combusting mode such that all flow sulfur is melted and consumed during the emplacement event. Further, thermal erosion during emplacement results in pits and channels that mark the passage of the combusting flow. These thermal erosion pits and channels are typically littered with non-combusted silicate blocks, show overhanging rims and an absence of sulfur. If activity remains confined to a source fumarole basin, then sulfur lake activity will result. Combustion of such a feature leaves thermally eroded pits, typically a few tens of centimeters to a few meters wide and long, and a few tens of centimeters deep. However, the increase in sulfur volume during melting and erosion of pit walls mean that overflow and breaching is common. This leads to capture of new sulfur encrusted fumarole basins and flow extension. Flow extension away from the lake results in thermal erosion channels as much as 1.7 m wide, 0.6 m deep and 23.5 m long. Flow direction is dictated by slope, cinder ejection and sources of new sulfur, thus flows are capable of moving down, across and/or up slope if that is the dominant source of new sulfur. We estimate that sulfur flow activity has combusted 2,000–5,000 m3, or 4,000–10,000 tons, of sulfur at Vulcano. Only one noncombusted unit could be found during seven fumarole-fieldwide surveys during 1998–2003; this was 7.3 m long and 0.3 m wide, and had a viscosity of 0.1–40 Pa s. This viscosity is consistent with emplacement temperatures of 165–180°C, which are lower than sulfur’s combustion temperature. At Vulcano the commonality of thermal erosion features over noncombusted sulfur flow units indicates that combusting emplacement has been the main mode of flow emplacement at this volcano. The common occurrence of combustion is also evident from reference to the same phenomenon by Deodat de Dolomieu in 1783.

Silicate Thermal Insulation Material from Rice Hull Ash

Silicate blocks were produced from rice hull ash (RHA) derived sodium silicate, and physical properties and thermal conductivity of the blocks were investigated. A Sodium silicate solution was produced from RHA by solublizing the silica in 1 M NaOH at 100 °C, followed by filtering to remove the carbon residue. The silicate solution was then boiled at different heating rates to evaporate the water and produce highly porous thermal insulation blocks with varying densities. X-ray diffraction patterns demonstrated the amorphous nature of silicate blocks. FTIR spectra demonstrated the presence of the silicate network in the silicate. Block density, mechanical strength (the compressive force per unit area required to break the block), and thermal conductivity decreased with increasing heating rate. The block density, mechanical strength, and thermal conductivity of silicate blocks were 0.33−0.42 g·cm-3, 145−196 N·cm-2, and 0.103−0.128 W·m-1·K-1, respectively. Data suggested that RHA could be used to produce the...

ERGONOMIC ASSESSMENT OF MANUAL BUILDING WORK ASSOCIATED WITH LIFTING TASKS/RANKŲ DARBO STATYBOJE, KELIANT MAŽAGABARIČIUS SUNKIUS ELEMENTUS, ERGONOMINIS VERTINIMAS

The purpose of these studies is to reduce the amout of low back pain as well as work injuries. Low back pain is more likely to occur if the load exceeds the worker's physical capabilities. In this paper, biomechanical criterion was based on calculating the compressive forces in the L5/S1 disc (Eqs (1), (2)). Three types of activity were taken into consideration. First, manual lifting granite plates (500× 500× 100 mm) with and without special devices (Figs 1, 2). Second manual lifting porous silicate blocks (300 × 600 × 200 mm). Third, manual lifting silicate brick in stooped postures. The investigation results presented in Fig 6 show clear benefits of ergonomic solutions for manual lifting heavy construction elements. The risk for back injuries becomes quite insignificant when ergonomic lifting devices are used (Fig 6 point f and g). These devices do not reduce the weight of lifted elements, but in case of a pneumatic device the total lifting weight is considerably increased, but the positive effect is achieved due to reducing moments because workers perform the task with a straight back. The reloaders of bricks usully feel back pain due to extreme repetitive bending of the back.

THE CRYSTAL CHEMISTRY OF THE [M3 11 14] TRIMERIC STRUCTURES: FROM HYPERAGPAITIC COMPLEXES TO SALINE LAKES

The crystal structures of nacaphite, Na (Na,Ca) 2 (PO 4 ) F, a 5.3232(2), b 12.2103(4), c 7.0961(2) A, α 90.002(1), β 89.998(1), γ 89.965(1)°, V 461.23(5) A 3 , and quadruphite, Na 14 Ca 2 Ti 4 [Si 2 O 7 ] 2 (PO 4 ) 4 O 4 F 2 , a 5.4206(2), b 7.0846(2), c 20.3641(7), α 86.89(1), β 94.42(1), γ 89.94(1)°, V 778.54(7) A 3 , from the Khibina–Lovozero alkaline complex, Kola Peninsula, Russia, have been solved by direct methods for the holotype single crystals in the space groups P 1 ( Z = 4) and P 1 ( Z = 1) and refined to residual R values of 5.6 and 3.1%, respectively, using 2293 and 7303 observed (| F o | > 4σ F ) reflections collected with a single-crystal diffractometer fitted with a CCD detector and Mo K α X-radiation. Nacaphite is twinned; this twinning of the true nacaphite unit-cell emulates the C -centered unit-cell previously described for nacaphite. The chemical formulae of both minerals have been slightly revised. There is a close relation between the structures of nacaphite and quadruphite. The main fragment of the nacaphite structure is a cluster of three octahedra with a common F–F edge. These trimeric clusters link to form chains extending along [100] that are connected into a framework by (PO 4 ) tetrahedra. The structure of quadruphite consists of two structural blocks ( TS and AC ) stacked along [001]. The Ti silicate ( TS ) block has a three-layered structure consisting of a central sheet of octahedra and two adjacent Ti–Si sheets. The AC block of alkali cations can be described in terms of nacaphite-like trimeric clusters; as in nacaphite, these trimeric clusters link along [100] to form an infinite chain. Trimeric clusters of the form [ M ϕ 11–14 ], M = Na, Ca; ϕ: O, OH, F, Cl, are common in a group of alkali sulfates, phosphates (and silicates), occurring in sulphohalite, Na 6 (SO 4 ) 2 F Cl, galeite, Na 15 (SO 4 ) 5 F 4 Cl, schairerite, Na 21 (SO 4 ) 7 F 6 Cl, kogarkoite, Na 3 (SO 4 ) F, the synthetic compound (Na 2 Ca) (PO 4 ) F (a dimorph of nacaphite), arctite, (Na 5 Ca) Ca 6 Ba (PO 4 ) 6 F 3 , the synthetic compound Na 2 Fe (PO 4 ) (OH), polyphite, Na 17 Ca 3 Mg (Ti,Mn) 4 [Si 2 O 7 ] 2 (PO 4 ) 6 O 2 F 6 , and sobolevite, Na 11 (Na,Ca) 4 (Mg,Mn)Ti 4 [Si 2 O 7 ] 2 (PO 4 ) 4 O 3 F 3 . Bond-valence considerations suggest that Si analogues of some of these structures should be stable, and several phases of tricalcium silicate, Ca 3 (SiO 4 ) O, contain such trimeric clusters.

ERGONOMIC ASSESSMENT OF MANUAL BUILDING WORK ASSOCIATED WITH LIFTING TASKS

Summary The purpose of these studies is to reduce the amout of low back pain as well as work injuries. Low back pain is more likely to occur if the load exceeds the worker's physical capabilities. In this paper, biomechanical criterion was based on calculating the compressive forces in the L5/S1 disc (Eqs (1), (2)). Three types of activity were taken into consideration. First, manual lifting granite plates (500× 500× 100 mm) with and without special devices (Figs 1, 2). Second manual lifting porous silicate blocks (300 × 600 × 200 mm). Third, manual lifting silicate brick in stooped postures. The investigation results presented in Fig 6 show clear benefits of ergonomic solutions for manual lifting heavy construction elements. The risk for back injuries becomes quite insignificant when ergonomic lifting devices are used (Fig 6 point f and g). These devices do not reduce the weight of lifted elements, but in case of a pneumatic device the total lifting weight is considerably increased, but the positive effe...

Complex reconstruction of a direct-heating glass-melting furnace

Complex reconstruction of direct-heating glass-melting furnace No. 4, heated with natural gas, at the Kamyshinsk Glass Container Plant had the purpose of first, converting the furnace previously designed for production of glass tiles, to production of silicate blocks and second, increasing the thermal efficiency of the furnace by more than two times. The complete reconstruction project includes two stages. The first stage is reconstruction of the furnace with installation of a bucket-type regenerator designed by the Tekhenergokhimprom Scientific-Industrial Association for heating air fed for burning the fuel to a temperature of 450{degrees}C; introduction of a system for flat-flame combustion of natural gas using double burners designed by the SSRIG, which decrease the area of the melting zone of the furnace by 36% (from 2.5 x 10 to 2 x 8 m).

Charges on the surfaces of two chlorites

AbstractTwo chlorites, sheridanite and clinochlore, have been examined to determine their surface charge characteristics. In order to increase their surface area and to produce a measurable surface charge, the chlorites were treated with 10−3m, 10−2m, and 10−1m HCl in 10−2m MgCl2 solutions. These treatments are shown not to alter the crystallinity of the chlorites and to produce a small pH-dependent negative charge which is not directly related to the total surface area. The clinochlore, (Si6.13Al1.84)(Al1.53FeIII0.53FeII0.18Mg9.52)O20(OH)16, is more readily attacked by the acids than the sheridanite, (Si5.43Al2.55)(Al2.90FeII0.05Mg8.86)O20(OH)16, and also produces material with greater surface area and pH-dependent, negative, surface charge. It is concluded that: (i) isomorphous substitutions in the lattice are not reflected in a permanent surface charge; (ii) the observed surface charge arises not only at the edges of the particles but also at points where the chlorite is predisposed to attack by acids; (iii) in the chlorite-acid system used, anions—probably mainly silicate—block positively charged sites.

Mullite ? Siliceous concrete with a phosphate bond for tunnel kiln car bases

Tests of mullite — siliceous concrete blocks with phosphate bonds for the bases of tunnel kiln cars showed that the block lining lasts 1.5–2 times longer than brick linings.

A geological interpretation of the lunar surface

This interpretation of lunar surface features is based on the differentiation of siliceous and basaltic substances similar to those of the earth. Our hypothesis is that lunar maria are composed of basaltic matter similar to that of terrestrial ocean basins, and that the lunar continents (bright regions) are composed of siliceous blocks.

On the Pipes or Sand-galls in the Chalk and Chalk-rubble of Norfolk

In a paper read before the Society in the Session of 1842–3, and intitled “On Pipes or Sand-galls in Chalk” I have shown that, in the county of Kent, these cavities in the chalk have, in their upper part, a longitudinal extension, and are connected with furrows which traverse the upper surface of the chalk, and which widen and deepen as they approach the pipes. From the nature of the materials with which these cavities are filled, I inferred that, in that county, they were formed before the deposit of the oldest Eocene strata. From the fact, also noticed by me in the same county, that similar furrows and pipes, though of smaller dimensions, occur in the blocks of siliceous sandstone which are dispersed through the superficial deposits, and are derived from the sands of the plastic clay, I concluded that these cavities were caused, not so much by the chemical as by the mechanical action of water; and, from the further observations I made, that still smaller furrows and pipes are actually in the course of formation on the surface of similar siliceous blocks on the coast of Kent, I judged that the mode of this mechanical action was by the flux and reflux of waves breaking on the shore.