Tertiary Origin Research Articles

Origin of oils in Po Basin, Northern Italy

The crude oils of the Po Basin are characterized by means of different analytical techniques (capillary GC of the saturated and aromatic hydrocarbons, carbon isotopic composition of the fractions, capillary GC/MS of the steranes and terpanes, V and Ni content). The geochemical data allow to sharply discern three main genetic groups, one in the Pedelpine area (Malossa group) and two in the Pedeapennine area (Cortemaggiore and Cavone groups). Furthermore two other oils are distinguished: one in the Pedealpine area(Gaggiano), slightly different from the Malossa group, and one in the Pedeapennine area (Bagnolo), peculiar for its terpane distribution. Extract of rock samples, from units which show the best source rock characteristics, were also studied in order to establish oil-source rock correlations. The “Riva di Solto” Argilite (Triassic) was found to be the primary source for the Malossa oil group. The “Marnoso Arenacea” (Tertiary) is recognized as the source rock for the Cortemaggiore oil group; the presence of oleanane in both oil and rock extract was a key point for the conclusive evidence for the source of this oil. For the Cavone group a Triassic carbonate, a sulfur rich kerogen is inferred as the probable source rock. The Meride Limestone (Triassic) is the source rock for the Gaggiano oil, whereas for the Bagnolo oil a possible Tertiary origin is suggested. This case history provides another record of the occurrence of oleanane in oils generated by Tertiary source rocks containing organic matter of continental origin.

Distribution of Palygorskite in Sediments and Soils of Eastern Saudi Arabia

AbstractRock samples representing different soil parent materials from the Jurassic, Cretaceous and Tertiary periods in eastern Saudi Arabia were investigated for their mineralogical and chemical properties. Samples from five soil profiles found on these rocks also were studied. Palygorskite was found to be the dominant mineral in the clay fraction of the Tertiary and upper Cretaceous sediments. Some shales of Tertiary origin contained mainly palygorskite with minor amounts of gypsum and soluble salts. Palygorskite was not found in any sediments of the early lower Cretaceous and Jurassic periods, and kaolinite was the dominant mineral in the clay fraction of those sediments. Soils associated with Jurassic limestone near the Riyadh area also showed a predominance of kaolinite in their clay fractions. However, the clay fractions of the soils found on Tertiary sediments in the eastern part of the country were dominated by palygorskite. The presence of palygorskite in the soils paralleled its presence in the parent materials or the rocks exposed in the area. Eolian transport of palygorskite was found to be a factor for the occurrence of palygorskite in the soils. Thus, the major portion of the soil palygorskite probably originated from the Tertiary sediments in eastern Saudi Arabia.

The formation of allyl sulphides by phenylthio-migration: control by silicon

When γ-silyl-β-phenylthio-alcohols are treated with acid, the strategically placed silyl group encourages the rearrangement of the phenylthio-group, both from a secondary migration origin to a secondary migration terminus, and from a secondary migration origin to a tertiary migration terminus (4)→(6). Geraniol/nerol (12) and linalool (14) have been synthesised from a common intermediate (11) using this type of reaction. Phenylthio-migration from a tertiary migration origin (17)→(3) can be controlled to a limited extent by a suitably placed silyl group, but it is easier to achieve direct β-elimination of the silyl and phenylthio-groups (17)→(18).

All clear for irradiated potato: Palmer, A. K., Cozens, D. D., Prentice, D. E., Richardson, J. C., Christopher, D. H., Gottschalk, H. M. & Elias, P. S. (1979). Reproduction and longevity of rats fed on an irradiated potato diet. Toxicology Lett.3, 163

An extended overview of the phase–mineral and chemical composition and classification of biomass ash (BA) was conducted. Some general considerations related to the composition of BA and particularly problems associated with this issue were discussed initially. Then, reference peer-reviewed data including phase–mineral composition and properties of BAs plus own investigations were used to describe and organise the BA system. It was found that BA is a complex inorganic–organic mixture with polycomponent, heterogeneous and variable composition. The phase–mineral composition of BA includes: (1) mostly inorganic matter composed of non-crystalline (amorphous) and crystalline to semi-crystalline (mineral) constituents; (2) subordinately organic matter consisting of char and organic minerals; and (3) some fluid matter comprising moisture and gas and gas–liquid inclusions associated with both inorganic and organic matter. Approximately 229 forming, major, minor or accessory phases or minerals were identified in BA. These species have primary, secondary or tertiary origin in the combustion residue and they are generated from natural (authigenic and detrital) and technogenic phases or minerals originally present in biomass. Common topics related to BA such as: terminology clarification; chemical composition; contents and concentration trends; correlations and associations; formation and behaviour; fusion temperatures; and leaching; were discussed and compared to coal ash. A general characterization of the phase–mineral composition and description of the occurrence and origin for common constituents in BA, namely: (1) silicates; (2) oxides and hydroxides; (3) sulphates (plus sulphides, sulphosalts, sulphites and thiosulphates); (4) phosphates; (5) carbonates (plus bicarbonates); (6) chlorides (plus chlorites and chlorates); (7) nitrates; (8) glass; (9) other inorganic phases; (10) organic phases; and (11) organic minerals; were also conducted and compared to coal ash. Finally, certain major associations related to the occurrence, content and origin of elements and phases were identified in the BA system and they include: (1) Si–Al–Fe–Na–Ti (mostly glass, silicates and oxyhydroxides); (2) Ca–Mg–Mn (commonly carbonates, oxyhydroxides, glass, silicates and some phosphates and sulphates); and (3) K–P–S–Cl (normally phosphates, sulphates, chlorides, glass and some silicates and carbonates). It was found that these systematic associations in BA have a key importance in both fundamental and applied aspects, namely their potential application for classification and indicator purposes connected with innovative and sustainable processing of BA. The potential utilization, technological and environmental advantages and challenges related to BA using the above classification approach are described in Part 2 of the present work.

Microfungi of St Kilda

In 1971 Watling and Richardson published an account of the Agarics of St Kilda in relation to the higher plant communities of Hirta and Dun, listing 162 species, including several ectotrophic mycorrhizal fungi associated with Salix repens. Hitherto the remaining groups of fungi have not been recorded. This small cluster of islands of Tertiary volcanic origin, isolated in the North Atlantic nearly 40 miles west of North Uist and near the edge of the continental shelf, is too windswept to support trees and even the usual woody substrata of the Hebrides, bramble and gorse, are lacking. Hence, in spite of the mild damp climate, there are even fewer opportunities for the establishment of a rich microfungus flora than in the Long Island. The following list comprises those obtained during a week's collecting towards the end of September 1978. Five species of Agaricales additional to the Watling and Richardson list and to the writer's collections from the Long Island are also included.

The New Zealand short-tailed bat,Mystacina tuberculata; a review of present knowledge

Abstract Research on the New Zealand short-tailed bat is reviewed from published and unpublished studies. The monotypic family Mystacinidae, at present assigned with the Vespertilionidae and Molossidae to the Vespertilionoidea, is considered to be best re-associated with the Emballonuridae and Noctilionidae in the Emballonuroidea. The two subspecies of Mystacina tuberculata Gray are retained pending elevation to specific status. The dichotomy of Mystacina stock probably occurred in the Pliocene, with the lesser short-tailed bat (M. t. tuberculata) and the greater short-tailed bat (M. t. robusta) evolving north and south respectively of the Pliocene Manawatu Strait at the onset of Pleistocene cooling. Mystacina has no known fossil record, and its origin and phylogeny are uncertain. The possibilities of an early to mid Tertiary origin in Antarctica, Australia, or South America and of an earlier Cretaceous origin in Gondwanaland are discussed. Mystacina feeds seasonally on forest fruits, pollen, and nectar, ...

The Fungi of the Azores

The Azores form an archipelago 480 km long, of volcanic islands rising from a submarine ridge. The nearest island to Europe is about 1500 km from Gibraltar, 1250 from Cabo da Roca in Portugal and about 1900 from the English Channel; from the westernmost island it is about 1750 km to Newfoundland. These are truly oceanic islands, of tertiary origin, which have never been in contact with any major land mass and all organisms found on them must have reached them across a wide expanse of ocean.* They have, however, been colonized by Europeans since the I5th century; most of the present woody vegetation consists of introduced trees and shrubs and there has obviously been ample opportunity over a very long period for the accidental introduction of fungi by human activity. The islands fall into three groups, an eastern composed of Sio Miguel and Santa Maria, a central composed of Terceira, SAo Jorge, Graciosa, Pico and Faial and a western of Flores and Corvo. From Santa Maria to Madeira is 740 km, from Sao Miguel to Terceira 12o km. Santa Maria and Graciosa are low lying but most of the islands rise steeply to about 900 m while Pico has an impressive conical peak 2373 m high. The climate resembles that of the Hebrides, with frequent gales, copious rain and a high relative humidity. The mean annual rainfall near the sea at Ponta Delgada is 635 mm and rainfall is considered to increase by 20 per cent every 90 m above sea level. Frost occurs occasionally at 500 m and over, though never on the coast, and owing to frequent mist and low cloud, land above 300 m is always more or less wet, with mean relative humidity seldom falling below 88 per cent. Hence, though the islands are densely inhabited, with housing almost continuous wherever the coastal belt is level enough, permanent habitation above 300 m is regarded as impracticable because of the mist. Though the lavas are alkaline, the high rainfall and extensive leaching of bases renders the soils naturally acid and thin development of Sphagnum occurs in places on the high ground. Some hill pasture, however, has been improved by stripping, fertilizing and reseeding with Lolium and Trifolium repens. The principal industry is cattle raising and the scenery away from the villages is strongly reminiscent of west Wales or north Cornwall, with small green grass fields enclosed by dry stone walls. The native woodland contained few species, notably Myrica faya, Laurus azorica, Juniperus brevifolia and Erica azorica. It has now largely disappeared except from comparatively recent lava flows with a surface too rugged for exploitation. Pittosporum undulatum is now naturalized throughout the archipelago and forms a dominant low

Clay Mineralogy and Solutions to The Clay Problems in Norway

If you think that gate, trough, and ditch, cow grate, and possum belly all belong down on the farm, think again. They have a lot to do with getting the gumbo out, and that has a lot to do with faster, cheaper drilling. Introduction One of the major problems confronting operators developing the Norwegian sector of the northern North Sea is the presence of soft, sticky, gumbo clays. These clays, of Recent to Tertiary origin, are encountered downwards from the sea bed to the Lower Eocene. A gradual transition from well defined clay to shale occurs in the Lower Eocene. Instantaneous penetration rate through these intervals is high. Drilling rates penetration rate through these intervals is high. Drilling rates for the 17 1/2 -in. hole often exceed 2 to 4 minutes per joint (to 5,000 ft), and the 12 1/4-in. hole can be drilled in 6 to 12 minutes per joint (to 9,000 ft). Hole making itself is rapid, but problems associated with the drilled clay cuttings are serious and time consuming. For example, as shown in Fig. 1, actual rotating tie (including time spent opening the surface hole) for Well B to a depth of approximately 8,500 ft was 101 hours. The time spent for other operations related to drilling amounted to 190 hours, or almost twice the time spent rotating. Most of the 190 hours was spent circulating and conditioning, pumping out clay rings, cleaning mud ditches loaded with clay balls, and cleaning blinded shaker screens. This paper assesses the gumbo problems, explains the steps-that were taken to overcome those problems, and tells what equipment is recommended problems, and tells what equipment is recommended and what mud characteristics are desirable. Occurrence of Swelling Clay as a Function Of Clay Density In a recent study by Burst on Gulf Coast clayey sediments it was proposed that water migrates from the clay in three separate stages of dehydration during the geological development of the clay. The data given in Fig. 6 of Burst's paper have been replotted to show the percentage of swelling clay at any stage of its geological development and are presented in Fig. 2. This illustration shows the percentage of swelling clays, nonswelling clays, pore water, and interlayer water present in a typical clay or shale during the process of diagenesis. The total water content reflects both pore water and interlayer water. The total water plus the sum of clayey and nonclayey material at any stage of development constitute 100 percent. percent. The percentage of swelling clay reaches a maximum of about 40 at the end of the first stage of dehydration when most of the pore water and interlayer water has been removed by overburden pressure. Porosity and total water decrease as density pressure. Porosity and total water decrease as density increases. Percentagewise, the interlayer water is also at a maximum at the end of the first stage of dehydration. The clay has a density of about 1.96 gm/cc and a total water content of about 30 percent. Swelling clays in excess of 35 percent may be expected for clays with an over-all density of 1.7 to 2.1 gm/cc. The density of clays observed in Norway has consistently been within this range for the interval between 1,500 and 8,500 ft. We should expect to find a large proportion of swelling clays when the clay densities are less than 2 gm/cc. JPT P. 25

Distribution and Directional Fabric of Ash-Flow Sheets in the Northwestern Mogollon Plateau, New Mexico

Individual ash-flow sheets distributed over wide areas in the Mogollon-Datil volcanic province can be delineated and related by flow direction techniques to specific source cauldrons. Two major mid-Tertiary ash flows in the Mogollon Plateau have measurable microscopic directional fabric indicative of primary flow direction imprinted in the ash-flow sheets during late-stage laminar flow. Regional stratigraphic relationships and flow patterns of the ash-flow sheets indicate a late Tertiary origin of the Mogollon Plateau depression. They also show that Basin-Range faulting in southwestern New Mexico was not initiated until after emplacement of the younger ash flow (23 m.y. B.P.). Directional fabric is an inherent property of many calc-alkalic ash-flow sheets and measurement of preferred orientation provides a powerful tool in unravelling the geologic history of complex volcanic terrane.

Characteristics of Oil Provinces: A Study for Students

ABSTRACT Important differences are discernible between oil basins wholly of Tertiary origin (like some Californian basins) and basins of Mesozoic origin nonethless producing from Tertiary rocks (like the Maracaibo basin). Both sets of basins differ in multiple ways from productive Palaeozoic basins. It is suggested that the differences are due primarily to distant migration, which has enabled oil in older sediments to become pooled far out on the forelands, in shelf sediments and non-orogenic traps, whereas Tertiary oils are still in their basins of origin and in traps of orogenic generation. Combinations of Mesozoic and Palaeozoic oil are much rarer than combinations of Mesozoic and Tertiary oil. It is suggested that this has two causes: the spacing of orogenic episodes, which left the first half of Mesozoic time essentially quiescent, and the introduction of a totally new basin-creating mechanism during late Mesozoic time. This involved the creation of extensional basins consequent on continental drift. As oil geologists have been traditionally resistant to the drift hypothesis, it is very likely that there are more new oil provinces still to be found in Mesozoic rocks than in either Tertiary or Palaeozoic. It is also likely that the familiar association between Tertiary oil basins and Tertiary orogenic belts has obscured the fact that the Mesozoic extensional basins opened up by drift continued to be basinal during the early Tertiary; the Gulf Coast is the familiar exemplar. Wherever a large delta was built outwards over the Tertiary breakover between continental and oceanic crust, equally good prospects should be provided. But if the locales are far removed from the Alpine orogenic belts, they will lie well off shorelines defined by the postglacial rise of sea level. The ideal source sediment is deduced to be one that characterizes many oil provinces and is conspicuously rare or absent in other regions -- a dark-coloured, phosphatic pelite or marl, with organic remains almost entirely planktonic or nektonic and almost wholly microscopic except for fish remains.

Sulfur Isotope Abundances and Genetic Relations of Oil Accumulations in Middle East Basin

A sulfur isotope study was made of sulfur in crude oils from various northern Iraq oil fields and of sulfate sulfur of gypsum and anhydrite deposits in the Arabian Gulf-Iraq-Iran basin. The sulfur isotope ratios (S34/S32) of 42 oil samples from Tertiary and Cretaceous reservoirs were found to be very uniform, the average ^dgrS34 value being --5.4 ^pmil, relative to Canyon Diablo troilite. By contrast, three oils from reservoir rocks of Triassic age showed a distinctly different S34/S32 ratio, the average ^dgrS34 being +2.4 ^pmil. The isotopic composition of oils from different depths--one above the other--is particularly uniform. In the Kirkuk field, oils from four levels--Tertiary and Upper, middle, and Lower Cretaceous--are identical within the reproducibility of the determinations (^dgrS34 = --5.5 ^pmil). In the Bai Hassan field, ^dgrS34 = --7.25 ^pmil for oils from the same four levels. These findings give strong support to Dunnington's view that the major oil accumulations in Cretaceous and Tertiary traps in northern Iraq originated from a common source. The sulfur isotopic composition of contemporaneous marine sulfates can be considered representative of the level from which isotope fractionation started. As a result of fractionation, reduced sulfur present as organic compounds in the oils is depleted in S34 relative to the sulfate from which it was formed. On the basis of ^dgrS34 values for Jurassic, Cretaceous, and Tertiary evaporites of the Middle East, a Jurassic origin for the oils is most favored, and a Tertiary origin is least likely.

Vegetation of the Guadalupe Escarpment, New Mexico‐Texas

The Guadalupe Escarpment, a Persian limestone reef, is the eastern face of a semiard—mesothermal mountain mass that rises 1,000—4,000 ft above the southwestern edge of the Great Plains. Phytocenoses range from xerophytic (Larrea, Flourensia, Acacia dominance types) on the Silty to gravelly plains, through less xerophytic (Agave, Dasylirion, Juniperus dominance types) on gravelly to bouldery lower slopes, to comparatively mesophytic (Juniperus, Quercus, Pinus dominance types) on rocky upper slopes and the escarpment peneplain. This general gradient is a vegetational continuum in which species' ecologic amplitudes are distinct but form overlapping assemblages of similar structure. Special environmental gradients are produced by topographic discontinuity. On low elevation canyon slopes, south—facing exposures support more xerophytic dominance types than north—facing exposures, although floristic differences are minimal. At highest base levels and slope elevations, south—facing exposures support the most xerophytic of all canyonside vegetation, and floristic differences between slopes are maximal. Dominance types with a tree stratum are well developed inside canyons; they form a continuous streambed—stream terrace—canyonhead sequence of increasing mesophytism. Canyon depth and water are important in supporting relict woodland dominated by Acer, Quercus, Juniperus, and Juglans. Height and coverage as stratal features plus growth contribute to a synusial description of the vegetation. Based on relative concordance of synusiae, shrub desert, succulent desert, evergreen woodland, and deciduous woodland plant formations are present. Microphyllous vs. succulent—semisucculent shrubs and half—shrubs distinguish the two desert formations. Narrow and broadleaf evergreen trees vs. broadleaf deciduous trees distinguish the two woodland formations. A mid—gradient predominance of structural diversity characterizes the ecosystem. Comparisons with other southwestern desert regions reveal that dominance types vary considerably; but the same formations recur, although in differing patterns based largely on regional edaphic differences. Formations are shifted toward the xerophytic end of an environmental gradient in the igneous—based Chisos Mountains, Texas; and succulent desert is not well developed on the north side of these mountains. Succulent desert of the Chihuahuan Desert region may not be classable with that of the Sonoran Desert region, because a tree stratum is added in the latter region. Succulent desert and evergreen woodland of the Guadalupe Escarpment could have had a common Madro—Tertiary origin based on evergreen—succulent dominance and paucity of deciduous growth forms.

Stratigraphic and Structural Controls of Bituminous Sandstone Deposits of Utah: ABSTRACT

The bituminous sandstones of Utah contain very significant reserves of oil which can add substantially to overall United States oil reserves. An understanding of the origin of the bitumen, the nature of the reservoir rock, and the mechanics of emplacement will lead to a more intelligent exploration program and to a more efficient development of the deposits. All of the bituminous sandstone deposits of commercial importance are located in the eastern half of the State of Utah. The largest of these is the Sunnyside deposit located in Carbon County. Next in order of importance are the deposits of the Asphalt Ridge area, the Whiterocks area, the Peor Springs deposits, and the bituminous sandstones of the Green River Desert. The reserves of these areas are much greater than pr viously estimated. The deposits in the Sunnyside--Peor Springs areas are stratigraphically controlled, occurring on a north-dipping monocline where the highly organic Green River Formation intertongues with the fluvial beds of the Wasatch Formation. Bitumen at Asphalt Ridge is contained in sandstone and conglomerate of the Eocene (?) Duchesne River Formation and in the basal sandstones of the Cretaceous Mesaverde Formation. In the former, bitumen beds saturation is related to unconformities and to faulting. In the latter, the saturation is related directly to progressive overlap and truncation, combined with structural folding. A Cretaceous source for the saturation in the basal Mesaverde beds is now proposed in view of new data rather than a Tertiary origin as interpreted previously. Th accumulation of bitumen in the Navajo Sandstone of Jurassic age in the Whiterocks area, previously believed to have been primarily the result of stratigraphic controls and of Tertiary origin, is postulated to be of Paleozoic origin and the result, primarily, of strong structural control. The localization of bitumen in the Tertiary beds of the Chapita Wells--Dragon--Rainbow--Pariette Bench areas of the Uinta basin is related directly to good porosity and permeability within a reservoir associated with relatively strong structural controls, including both fracturing and faulting. It is proposed that the high pour-point, high wax crude oil of the Red Wash--Walker Hollow--Wonsits--Brennan Bottoms--River Junction--Pariette Bench--Monument Butte oil fields represents the original, first-phas oil. The second-phase oil is represented by original entrapped oil which escaped upward when faulting and subsequent fracturing of the reservoir took place. The oil moved into the porous and permeable sandstones cut by the fractures and faults and, during erosion, the lighter fractions escaped. Because of the viscosity of the crude when the larger fracture systems opened, only a relatively small percentage of oil was able to move into the sandstone reservoirs. The greater volume was left in the fractures which remained open and, with more complete oxidation and subsequent induration, formed the many exotic hydrocarbons of the basin such as gilsonite, elaterite, wurtzilite, ozocerite, tabbeyite, and others. The difference in chemical composition is intimately associated with the sourc beds as stated in the literature; however, the mechanics of emplacement have heretofore never been explained adequately. The localization of bitumen in the Moenkopi, Kaibab, and the White Rim Formations of the Green River Desert area in central Utah is related directly both to structural and stratigraphic controls. Local entrapment of oil in post-Laramide structures was probably controlled by regional hydrodynamics, because a fairly well-defined asphalt-water contact is present. Furthermore, the best saturations occur on well-defined structural features. The origin of the oil undoubtedly was the Permian Kaibab Limestone or, where it is missing, the basal marine facies of the Moenkopi Formation. There are other areas of lesser importance where the relationship between the controlling par meter End_of_Article - Last_Page 1577------------

On the origin of the Caspian and Baikal seals and the paleoclimatological implication

Caspian and Baikal seals, as well as the ringed seal of Arctic waters, are classified, and fossils previously described and classified are discussed, with lectotypes given to prevent further confusion. In view of the classification, the fossil record, and the fact that the living varieties give birth to pups with white coats (an adaptation to birth on ice), a common ancestry is implied. It is suggested that the Caspian seal is probably of Tertiary origin, implying that ice must have formed at that time at least in some sections of northern seas, and that present varieties are relics of Tertiary connections with the northern seas rather than emigrants who migrated to present locales as a result of Pleistocene events.

Is the Channel of the Missouri River Through North Dakota of Tertiary Origin?

Introductory For years it has been believed that the Missouri River owed its present course very largely to the influence of ice-sheets. This was first recognized by General G. K. Warren in 1868. In 1916 Prof. A. G. Leonard, State Geologist of North Dakota, published his conclusion, after some years of study, that the channel of the Missouri through North Dakota was of Teritiary origin, and that the ice-sheets of the Pleistocene had little effect upon its course. This conclusion is diametrically opposed to that of South Dakota geologists; consequently the writer undertakes in this paper to show the errors of Dr. Leonard and, on the contrary, the reasons for believing that before the ice-sheet influenced the Missouri River the Missouri was made up of various streams leading to the north and east, and that the ice, by damming them, caused the water accumulating along its western edge to form . . .

On the Discovery of Flint Implements in the Drift at Milford Hill, Salisbury

S ince the discovery of flint implements in the higher-level gravel at Fisherton, on the west of this city, an interesting account of which was given by my friend John Evans, Esq., in a valuable paper published in the August Number of the Society's Journal, a second discovery of a large number of very excellent weapons has been made in the drift-gravel of Milford Hill, a deposit of the same age as the Fisherton Beds, but situated on the opposite side of the Avon, immediately to the east of Salisbury. In the Ordnance Map the name of Milford Hill has been erroneously applied to what is known on the spot as Cricket Down, Milford Hill proper being a continuation of Mizmaze Hill. The gravel in which these implements are found is composed of the ordinary subangular chalk-flints, a few well-rolled Tertiary pebbles, some small blocks of saccharoid sandstone, also of Tertiary origin, and a much larger percentage of fragments of Greensand chert than occurs in the gravel at Fisherton. All these materials are blended with. a variable proportion of sand and stiff clay, and are stained pretty uniformly of a dark-ferruginous colour. Many of the chalk-flints are of large size, with sharp, well-defined angles, and present scarcely any marks of violent rolline or water-wearing. When we look at any of the sections of chalk in this neighbourhood, and remark the comparatively few and widely scattered bands of nodules, we feel that one can barely form an adequate notion of the immense