Lowermost Zone Research Articles

Climatic and non-climatic lake-level changes inferred from a Plio-Pleistocene lacustrine complex of Catalonia (Spain): palynology of the Tres Pins sequences

A 27-m sequence of deposits from the Plio-Pleistocene Banyoles-Besalu lacustrine complex, at Tres Pins, N.-E. Spain, shows lithological, carbonate, pollen and spores, and ostracode-gastropod evidence of climatic and lake-level change. Upland pollen taxa from the lowermost zones 1, 3 and 5, show that the area was forested and indicate a progressive deterioration of the climate. Zone 2 (steppe vegetation) corresponds to a global glacial stage, with mild temperatures, if the comparison to modern analogues is valid. Only minor climate fluctuations occurred subsequently. Aquatic vegetation and micritic sediment facies show a pelagic environment during pollen zones 1 and 3 and a littoral one during pollen zone 5. A short-term lowering of the water level (sandy algal micrite and slightly brackish waters) occurred in zone 2, as a result of severe droughts. Subzone 2c records progressive recovery of the forest. The coarse lithology and the high carbonate content, however, continue to indicate shallow waters. The fluctuation marked by zone 4 (extensive marsh vegetation and spring waters) may be due to a lake-level decrease caused by karst activity, or by lower precipitation with only slight cooling, or more probably by a relative lake-level decrease caused by natural infilling. The sediment of pollen zone 4, a sandy algal micrite, indicates the development of a littoral bench at the core site. From pollen zone 4 to pollen zone 5 an evolution from lakeward to landward position occurred. In zone 2, droughts existed at least during the spring growing season, and probably also during the rest of the year. In subzone 2c, a shift to spring precipitation occurred. In contrast, during pollen zone 4, if there was a decrease in precipitation, it did not take place during the summer growing season.

Recent foraminiferal distribution in Freemansundet and Early Holocene stratigraphy on Edge�ya, Svalbard

The Present foraminiferal distribution (live + dead) in Freemansundet between Barentsoya and Edgeoya, Svalbard, has been compared with assemblages in raised marine Holocene deposits in Guldalen on Edgeeya. Four distinct foraminiferal assemblages were identified in Freemansundet, the Elphidium excavatum-Cassidulina reniforme assemblage, the Elphidium hallandense assemblage, the Cibicides lobatulus assemblage and the Elphidium incertum-Haynesina orbiculare assemblage. Four assemblage zones (Zones A-D) have been established in the glaciomarine to marine sediment sequence in Guldalen. Only two of the recent fauna! types were represented here. The Elphidium excavatum-Cassidulina reniforme assemblage, which reflects a proximal glacier environment, was found in the lowermost Zone A (the Elphidium excavatum Zone) and in Zone C (the Elphidium excavatum-Cassidulina reniforme Zone) in the Guldalen stratigraphy; the Elphidium incertum-Haynesina orbiculare assemblage, which reflects ameliorated shallow water conditions, was found in the uppermost Zone D in Guldalen. The marine sequence in Guldalen represents a relatively short period of time during the Early Holocene (ca 9700 to 8300 BP). The succession of the foraminiferal assemblages suggests that the deglaciation was interrupted by a cold period with glacial stagnation just after 9600 bp (Zone B. the Astrononion gallowayi-Nonionellina labradorica Zone).

Recent foraminiferal distribution in Freemansundet and Early Holocene stratigraphy on Edgeøya, Svalbard

The Present foraminiferal distribution (live + dead) in Freemansundet between Barentsøya and Edgeøya, Svalbard, has been compared with assemblages in raised marine Holocene deposits in Guldalen on Edgeeya. Four distinct foraminiferal assemblages were identified in Freemansundet, the Elphidium excavatum-Cassidulina reniforme assemblage, the Elphidium hallandense assemblage, the Cibicides lobatulus assemblage and the Elphidium incertum-Haynesina orbiculare assemblage. Four assemblage zones (Zones A-D) have been established in the glaciomarine to marine sediment sequence in Guldalen. Only two of the recent fauna! types were represented here. The Elphidium excavatum-Cassidulina reniforme assemblage, which reflects a proximal glacier environment, was found in the lowermost Zone A (the Elphidium excavatum Zone) and in Zone C (the Elphidium excavatum-Cassidulina reniforme Zone) in the Guldalen stratigraphy; the Elphidium incertum-Haynesina orbiculare assemblage, which reflects ameliorated shallow water conditions, was found in the uppermost Zone D in Guldalen. The marine sequence in Guldalen represents a relatively short period of time during the Early Holocene (ca 9700 to 8300 BP). The succession of the foraminiferal assemblages suggests that the deglaciation was interrupted by a cold period with glacial stagnation just after 9600 bp (Zone B. the Astrononion gallowayi-Nonionellina labradorica Zone).

Palynologie et paléoenvironnements des épisodes du Sable de Lotbinière et des Varves de Deschaillons (Pléistocène supérieur) de la vallée du Saint-Laurent

Lotbinière Sand and Deschaillons Varves are indicators of the drainage pattern of the St. Lawrence watershed, which presumably occurred during the Late Sangamonian (5c and 5c–5b transition?). The pollen content of the Lotbinière Sand suggests there was a Picea mariana – Betula – Pinus boreal forest in the valley. In the lowermost zone of the Deschaillons Varves, the pollen is very abundant: the boreal forest was progressively flooded by Lake Deschaillons. Above this zone, the vegetation seems to evolve toward a Picea and Betula open forest. The pollen of the upper contorted varves was presumably reworked from older material or transported from remote sources. The following paleoenvironmental sequence is reconstructed in the St. Lawrence Valley: (i) lowering of the relative drainage level, as indicated by the erosional disconformity in lower rythmites; this phase, of unknown duration, is ascribed to an eustatic lowering related to a global climatic cooling; (ii) an aggradation phase, as indicated by the Lotbinière Sand, before and at the beginning of a glacial damming in the middle estuary; (iii) progressive flooding of the valley and its boreal forest as ice caps are present on adjacent Laurentian and Appalachian highlands; (iv) expansion of Lake Deschaillons, limited by the Glens Falls sill, New York. The relative elevation of the lake was at least 56 m. Great Lakes and upper St. Lawrence River drainage system was probably deflected to the Hudson River. According to the number of varves, the regional ice caps preceded the general invasion by Laurentide Ice Sheet of approximatively 3800 years.

Holocene Paleoecology of an Estuary on Santa Rosa Island, California

The middle to late Holocene history and early Anglo-European settlement impacts on Santa Rosa Island, California, were studied through the analysis of sediments in a small estuarine marsh. A 5.4-m-long sediment core produced a stratigraphic and pollen record spanning the last 5200 yr. Three major zones are distinguishable in the core. The lowermost zone (5200 to 3250 yr B.P.) represents a time of arid climate with predominantly marine sediment input and high Chenopodiaceae and Ambrosia pollen values. The intermediate zone (3250 yr B.P. to 1800 A.D.) is characterized by greater fresh water input and high values for Asteraceae and Cyperaceae pollen and charcoal particles. The uppermost zone (1800 A.D. to present) documents the unprecedented erosion, sedimentation, and vegetation change that resulted from the introduction of large exotic herbivores and exotic plants to the island during Anglo-European settlement. The identification of pollen grains of Torrey Pine (Pinus torreyana) documents the persistence of this endemic species on the island throughout the middle to late Holocene.

Magnetostratigraphy of Pliocene Sediments From the Stirone River (Po Valley)

The Miocene-Pliocene and Pliocene-Pleistocene boundaries bracket a Pliocene section, approximately 800 m thick, along the Stirone river near Parma (Northern Italy). From the base to the top, the sequence consists mainly of blue clays (Zanclean in age), whitish laminates, silty clays and sandstones of Piacenzian age. A debris flow, which is the sedimentary expression of a hiatus, separates the Zanclean from the Piacenzian sediments. Thermomagnetic analysis, thermal evolution of magnetic susceptibility, acquisition and removal of anhysteretic and isothermal remanent magnetization (ARM and IRM) by alternating field and thermal methods, X-ray diffraction and scanning electron-microscopy (SEM) have been used in conjunction to try and unravel the complex magnetic mineralogy of the Stirone samples. Two major carriers of the magnetic remanence appear to be pseudo-single domain (PSD) magnetite and high-coercivity pyrrhotite in varying amounts and grain sizes. Five different magnetic indicators yield roughly consistent logs, with magnetite being important in the lower part of the section and pyrrhotite becoming dominant upsection. Six zones with more or less uniform properties have been outlined. Except in the lowermost zone where magnetite is also an important carrier, pyrrhotite in the 150-350°C range is taken to be the main carrier of the characteristic and, we believe, primary magnetization. The overall mean direction for about 200 samples is D = 0, I = 52 (ag5 = 3), corresponding to a lack of local rotation about a vertical axis but implying some 10 of inclination shallowing. The magnetostratigraphy encompasses ten successive polarity zones. Correlation of magnetic and biostratigraphic results to the geomagnetic polarity time scale and to the biozonation of the Mediterranean area leads to the proposal that the Thvera subchron and part of the above reversed polarity zone are missing, as revealed by the absence of the Sphaeroidinellopsis seminulina s.1. Zone and by the occurence of Globorotalia margaritae from the very base of the section. The Sidufjall and Nunivak subchrons are recognized and the first occurrence of Globorotalia puncticulata occurs just above Nunivak subchron. The Cochiti subchron is observed next. A remarkable hiatus involves the upper part of the Gilbert chron up to the lower part of the Kaena subchron based on the record of the last occurrence of G. margaritae and G. puncticulata and the first occurence of G. aemiliana and G. bononiemis. Another hiatus involving the Reunion and Olduvai subchrons is suggested to occur in the upper part of the Pliocene sequence based on the absence of the G. inflata Zone and on the first occurrence of'Artica islandica, which marks the Pliocene/Pleistocene boundary, towards the top of the section. The average sedimentation rate is estimated to be 450-500 m Ma-' for the early Pliocene and 200-300 m Ma-1 for the late Pliocene. Despite highly non-uniform sedimentation, both reflecting the episodic nature of coupled tectonic and sedimentary processes on 359 Downloaded from https

Ostracod biostratigraphy and palaeoecology of the Kokoamu Greensand and Otekaike Limestone (Late Oligocene to Early Miocene), North Otago and South Canterbury, New Zealand

An improved Mid Tertiary ostracod stratigraphy has been obtained from detailed sampling of four outcrop sections of Kokoamu Greensand and overlying Otekaike Limestone in the South Island, New Zealand. The sections include the stratotypes and reference sections for the New Zealand Duntroonian and Waitakian Stages (Late Oligocene to Early Miocene). Three key evolutionary events provide the main basis for correlation of the sections, and allow recognition of four zones. These events are, from oldest to youngest: the first appearance of Cytheralison amiesi, at about the Whaingaroan/Duntroonian Stage boundary; the last appearance of Agrenocythere? semivera, together with a major faunal replacement, in the lower Duntroonian; and the first appearance of Trachyleberis jilletti sp. nov. at the Duntroonian/Waitakian Stage boundary. The lower boundary of the lowermost zone and upper boundary of the uppermost zone are not defined since they occur beyond the limits of the sequence. This correlation is consistent with ...

High-resolution immunolocalization of osteopontin and osteocalcin in bone and cartilage during endochondral ossification in the chicken tibia.

The ultrastructural distribution of two noncollagenous proteins, osteopontin (OPN) and osteocalcin (OC), originally extracted from bone matrix and proposed to play an important role in bone formation, was examined in the matrices of bone and cartilage from embryonic and postnatal chicken tibial growth plates by high-resolution immunocytochemistry using the colloidal gold technique. In bone, immunolabeling patterns using polyclonal antibodies against chicken OPN and OC were generally similar in that both showed an intense, but regionally variable, labeling of mineralized bone matrix and small mineralization loci dispersed throughout the osteoid and containing prominent condensed organic material. Unmineralized osteoid showed weak-to-moderate labeling. In the mineralized bone matrix proper, labeling was predominantly associated with amorphous, electron-dense patches of organic material among the collagen fibrils. In growth plate cartilage, both proteins first appeared related to calcified cartilage in the hypertrophic zone, although the labeling patterns were somewhat different. For OPN, gold particles were mostly associated with an organic lamina limitans-like density containing condensed, filamentous organic matrix at the periphery of small nodules and large masses of calcified cartilage, with additional moderate labeling throughout the interior of the calcified cartilage. For OC, labeling was observed over filamentous structures throughout the calcified cartilage matrix, with some, but less, labeling at the periphery. In the lowermost zones of the growth plate, the major reaction using both antibodies was found over a layer of dense, amorphous organic material at the periphery of the calcified cartilage at the future bone/calcified cartilage interface, a labeling pattern that persisted following bone deposition at these sites. OPN and to a lesser extent OC were also concentrated in cement (resting, reversal) lines. Throughout the bone and cartilage of the tibia, cells of both the osteoblastic and the osteoclastic lineages were found directly apposed to labeled surfaces and lamina limitans of organic matrix containing OPN and OC. In summary, it is concluded from the immunocytochemical data presented here that the association of OPN and OC with mineralized regions of the extracellular matrices of bone and cartilage and the accumulation of these proteins at tissue surfaces and interfaces are consistent with the hypotheses that they play a role in the extracellular mineralization process per se and/or that they may mediate cell adhesion and dynamics.

Secondary Recovery from a Stromatoporoid Buildup: Devonian Duperow Formation, Ridgelawn Field, Montana: ABSTRACT

Ridgelawn field is located in Richland County, Montana, in the western part of the Williston basin. It is a multiple-pay field, with production from ordovician, Devonian, and Mississippian carbonates. Discovered in 1980, the field was recently unitized in the Devonian Duperow Formation for purposes of secondary recovery by waterflood. In this part of the Williston, the Duperow consists of a repetitive succession of shoaling-upward carbonate cycles, each deposited under increasingly restricted conditions on a shallow marine shelf. Production at Ridgelaw occurs from dolomites within one of these cycles, cycle IIIa. Three separate, laterally continuous porosity zones (here termed a, b, and c, from lowest to highest) are recognized and mapped individually in the field. The reservoir has a lensoidal geometry; porous dolomite thins and grades laterally into tight carbonate. The Duperow pool at Ridgelawn is a solution gas drive reservoir. Computer log analysis of the Duperow pay interval indicates an average true porosity of 11.8% and an average initial water saturation of 17.7%. Net pay, defined as greater than 5% crossplot porosity, averages 16.6 ft across the field. Petrographic analysis and log calibration suggests that different facies in each of the three porosity zones were preferentially dolomitized to create reservoir-qualitymore » rock; each is now a sucrosic dolomite with intercrystalline porosity. Porosity can be occluded (most often in the upper two zones b and c) by both calcite and anhydrite cements. The lowermost zone, a, is related to a stromatoporoid/coralline bank, and has excellent but highly variable porosity and permeability. The two upper zones, b and c, are more finely crystalline dolomite and represent shallower water depositional facies. Maps for each zone, including porosity, porosity-feet, net pay, and water saturation were constructed and used for equity determination in the unit.« less

Lithostratigraphy and sedimentology of a Lower Ordovician limestone sequence at Hälludden, Öland, Sweden

Abstract In order to achieve a useful lithological zonation of the Lower Ordovician (Arenig-Llanvirn) limestone sequence at Hälludden, N. Öland, a method of presence/absence analysis was used in combination with correspondence analysis. Also conventional modal analysis was tried, but proved less effective for zonation purposes. The zonation achieved at Hälludden is valid at least locally, as indicated by the results from a preliminary correlation analysis with a corresponding sequence on northern Öland (Hagudden). Based on the presence/absence analysis, the section at Hälludden is subdivided into seven more or less distinct zones representing different depositional environments. The four lowermost zones (I-IV) represent shallowing conditions, reaching subaerial conditions in zone IV, while the sediments of the overlying zones (V-VII) were laid down in a shallow to very shallow, mainly low-energy environment. There is a scarcity of readily interpretable structures and constituents in the sequence. Presence of spar, grain-support and polished glauconite grains are some of the high-energy criteria used in the study, while shallow-water conditions are recognized mainly through the composition of the biota. The sediments of Zone IV (the “ooid horizon”) display a complexity in composition and texture indicating a mixing of sediments with different affinities. Evidence of selective leaching indicates early diagenesis under subaerial conditions. The distribution of different morphologies of glauconite grains in the sequence reflects their polygenetic origin and, in the case of internal molds, probably also faunal changes. Differences in the Fe2+/Fe3+ ratio cause the color of the sediment to shift from red to grey in the lower part of the sequence. This is mainly a synsedimentary feature, related to time of exposure at the sea-bottom. The environmental models discussed assume deposition in a wide, shallow sea with very limited tidal movements.

Potassic Diagenesis of Cambrian Sandstones and Precambrian Granitic Basement in UPH-3 Deep Hole, Upper Mississippi Valley, U.S.A.

ABSTRACT The Mt. Simon Sandstone (Cambrian) in core from Hole UPH-3 in northwestern Illinois contains three distinct diagenetic zones. A zone with K-feldspar overgrowths characterizes the upper 51 m of Mt. Simon Sandstone. An intermediate, underlying sericite zone is about 126 m thick, and a lowermost feldspar zone is about 87 m thick. Authigenic K-feldspar in the Mt. Simon Sandstone occurs in several modes: overgrowths, rhombs, penetration-twinned crystals, chert-like aggregates surrounded by coarser K-feldspar, mosaics of anhedral to euhedral crystals, and as replacements of microcline. Sericite (I/S) occurs as pore-filling aggregates of minute flakes. Quartz overgrowths are common throughout these three diagenetic zones. K-feldspar was the first to form, closely followed by quartz, then by ericite, and lastly, possibly by a second addition of quartz overgrowth. The upper 6.1 m of Precambrian granite gneiss basement exhibits similar potassic alteration to the overlying Mt. Simon Sandstone. The uppermost 2.5 m of the basement rock is a probable weathering profile in which pedogenic clays were replaced by sericite (I/S) and chlorite. Sericite in the basement rock was likely formed during the same episode as in the Mt. Simon Sandstone, based on 18O values. Authigenic K-feldspar occurs as pore-fillings, overgrowths, replacements of microcline, and intergrown with phyllosilicate. Below the profile it partially replaces plagioclase. Similar potassic alteration of the Mt. Simon Sandstone of UPH-3 occurs in cores of both UPH-1 and 2, indicating a lateral extent of about 7 km. A K/Ar date of 394.6 ± 6 Ma was obtained from authigenic K-feldspar of the basal Mt. Simon Sandstone. This Early Devonian age is within the range of ages from authigenic K-feldspar in Ordovician tuffs of the Upper Mississippi Valley, suggesting that the K-feldspar is the product of a single, regional diagenetic event. K/Ar dates of 271.3 ± 4.6 Ma, 254.4 ± 4.6 Ma, and 214.1 ± 4.6 Ma were obtained from authigenic sericite of the Mt. Simon Sandstone. The Devonian age for the K-feldspar and Permian ages for the sericite are nearly coeval with times of uplift of the Findlay and Pascola Arches respectively. These diagenet c episodes are attributed to regional migration of basinal brines caused by groundwater recharge on these uplifted arches. Potassium for both the K-feldspar and sericite possibly came from the Michigan and Illinois basins, respectively. Devonian and Permian dates for potassic diagenesis possibly coincide with two episodes of Pb-leaching of basement rocks at 400 Ma and 260 Ma. Thus the potassic fluids may have leached Pb and Zn from Precambrian basement, particulary paleosols, and then formed Upper Mississippi Valley Pb-Zn deposits.

The influence of duration-of-inundation on development of a man-initiated Spartina alterniflora Loisel. Marsh in north carolina

The relative growth responses of a man-initiated Spartina altemiflora Loisel. marsh were monitored annually in four duration-of-inundation zones (4, 7, 9, and 11 h daily) during a 4-yr period following the 17-month establishment period, with another sampling 10 yr later. There was a general trend of maximum values for height, number of flowers · m −2, basal area, and aboveground standing crop to occur in the 7-h inundation zone and for these values to decrease in the 9- and 11-h zones at the end of the second growing season (17 months after planting). This trend was reversed from the third through the fifth growing seasons with height, number of flowers · m −2, and aboveground standing crop significantly higher in the longest (11-h) inundation zone. Although other angiosperms began invading the upper elevation, lesser inundated zones during the second growing season, populations were too small to sample until the following growing season (29 months after planting), when they constituted ≈40% of the aboveground standing crop in the uppermost (4-h) zone. The aboveground standing crop of the S. alterniflora-dommated 11-h inundation zone became stabilized by the third growing season, but the belowground material dry weight continued to increase in all zones through the fifth season when its rate of accumulation began to stabilize in the lowermost zones. Although the uppermost zone was dominated by Phragmites communis Trin. by the twelfth season, Spartina alterniflora dominated the other zones where it constituted more than three-fourths of the aboveground standing crop and had spread ≈ 30 m beyond the planting toward the open water of the estuary. The number of invading species present in the fifth season decreased by > 65% in the twelfth season, but the remaining invaders generally constituted relatively more of the aboveground standing crop by the twelfth season. Over the 12 seasons the experimental S. alterniflora planting developed into a marsh with the species composition dictated by the availability of disseminules of other angiosperms under the prevailing environmental conditions of duration-of-inundation and salinity.

Middle and Late Weichselian marine deposits at Nørre Lyngby, northern Jutland, Denmark, and their foraminiferal faunas

The marine Weichselian deposits at Nørre Lyngby are subdivided into four assemblage zones based on the content of benthonic foraminifera.The lowermost zone, the Bulimina marginata-Buccella frigida zone, is correlated with the upper part of the Older Yoldia Clay of Yendsyssel and inferred to be of Middle Weichselian interstadial age.The Elphidium subarcticum zone is correlated with the Lower Saxicava Sand and the Elphidium excavatum zone with the Younger Yoldia Clay of Vendsyssel. The E. subarcticum zone is found to be a sandy facies within the lower part of the E. excavatum zone at Nørre Lyngby. The foraminiferal faunas of these two zones indicate mainly artic climatic conditions. Radiocarbon dates show that the E. subarcticum zone and also a major part of the E. excavatum zone belong to late Middle Weichselian.The uppermost zone, the Elphidium albiumbilicatum zone, is correlated with the Upper Saxicava Sand. The foraminiferal faunas in this zone seem to indicate an amelioration in climate, and the deposit might be present the Late Weichselian Bølling interstadial.

A postglacial pollen diagram from Angmagssalik, East Greenland.

A pollenanalytic study of a mire at Angmagssalik, East Greenland (65°36'N-37°39'W) has been made in connection with a vegetation research of this area by F. J. A. DANIËLS (in prep.) and J. G. DE MOLENAAR (1974, 1976). Six pollen assemblage zones have been described. In the lowermost zone of the diagram we visualise a local vegetation complex of Salix scrub and Carex bigelowii grass heaths on fluviatile or colluvial sand deposits. This was probably followed by more chionophytic vegetations (heaths and showbed with Koenigia). At ca. 6000 B.P. (radiocarbon date) peat growth started: the pollen assemblage and the lithology reveal a Carex-Eriophorum mire vegetation with a.o. Comarum palustre and Sphagnum, Drepanocladus and Calliergon spp. After a second extensive zone with willow scrub and grass heaths again a mire vegetation developed, probably in rather recent time. The diagram offers some evidence for climatic fluctuations, recognised elsewhere in the arctic. During the so called "climatic optimum" (ea. 6000-2200 B.P.) the climate of East Greenland, like that of North Greenland, was presumably more oceanic (with peat growth) than in earlier and later periods. This is in contrast to the conditions in South and West Greenland. The width of the drift ice belt along the East Greenland coast is probably a very important factor for the climate of the coastal area.

BRYOPHYTE SUBFOSSILS OF A LATE-GLACIAL DEPOSIT FROM THE MISSOURI COTEAU, SASKATCHEWAN

Bryophyte and associated macro-subfossils were recovered from a kettle located in prairie southwest of Moose Jaw in the Missouri Coteau of southern Saskatchewan. The higher plants were discussed in an earlier paper.Three samples taken from the organic layer gave C14 datings ranging from 11,650 ± 150 to 10,270 ± 150 B.P.Sixteen species and one variety of Musci were recovered. Eleven of these were found in the lowermost zone at a depth of 510–450 cm. This zone was composed of bryophytes and higher plants characteristic of a modern Picea forest. Fifteen bryophyte taxa were recovered from the middle zone at a depth of 450–290 cm. The macro-subfossils in this zone are typical of a present-day Populus–Picea forest. No bryophytes were found in the upper layer, 290–280 cm characterized by higher plant macro-subfossils and pollen typical of a modern Picea forest.All bryophytes recovered belong to present-day taxa; however, many of the boreal species are not now found in the region as the southern margin of the boreal forest is now 200 miles to the north.

Sur la limite entre la partie inferieure ('Paleocene') et la partie moyenne ('Eocene') du Paleogene

Abstract The Paleocene-Eocene boundary is defined on the basis of planktonic foraminifera. The Globorotalia parva zone, the uppermost Paleocene zone, represents the Thanetian, at least in part, or Landenian stage, including the lower part of the Ilerdian stage of Hottinger and Schaub (1960). The G. subbotinae zone, the lowermost Eocene zone, is equivalent to the lower part of the Ypresian, Sparnacian, or Londonian stage, which includes the middle and upper parts of the Ilerdian stage.

Petrography of the Mesozoic Succession of South Wales

AbstractThe heavy mineral suites of the Trias, Rhaetic and lowermost zones of the Lower Lias in the Vale of Glamorgan of South Wales are described. The northerly coastline of the Mesozoic sea, roughly coincident with the present-day periphery of the Coalfield, consisted mainly of Carboniferous Limestone and in places, the Old Red Sandstone and Millstone Grit. The mineral assemblage at any particular point in the littoral zone was determined largely by the nature of the outcropping rocks of the coastal mainland, the derivation of detritus being very localized. Within this zone some degree of gravity sorting of the detritals occurred, this implying a relatively steeply inclined coastal sea-bed. An off-shore current carried detritus from the Armorican land-mass of Britanny and granite of South-West England to this area where the detritals were dispersed thinly throughout the locally derived sediment.

Occurrence of Durvillea caepestipes on Chatham Island

A BELT of Durvillea is a conspicuous feature of the upper sub-littoral to lowermost littoral zone of the coast of Chatham Island, as is usual in southern waters. On those parts of the coast visited, the dominant species is one with a solid lamina and not the D. antarctica (Chamisso) Hariot which is the dominant species on the coasts of New Zealand approximately five hundred miles to the west.