Search

The subsurface sediments of the Kerala coast provided signatures of hydrological processes that have influenced in the modifications and conversion of larger part of the lowland and the forest cover into a major wetland system during the Holocene which in turn has transformed into one of the best carbon sinks in the Indian subcontinent. The most significant and well recognized signature is the paleoflood event during the Early to Middle Holocene coinciding with the Holocene Climate Optimum (HCO). The excessive rainfall seems to have flooded the entire forest area in the coastal plains and the forests that flourished in the abandoned river channels and other low-lying areas in the midland. Formation of peat and peat land development in the inland region, but not far away from the coast, towards the Middle Holocene has been another important imprint of the hydrological process. Occurrence of peat sequence of 1–3 m at shallower depths stands testimony to such episodes. The other recognized imprints include the erosion and reworking of older sediments that contain the Neogene pollen elements and development of bay head deltas and other alluvial deposits in the mouth of the rivers. The mangrove dynamics too provided sufficient evidence of their prevalence, stability and decreasing tendency depending up on the hydrological regimes during the Holocene. Though episodes related to mud bank formation, as of now, are restricted to recent times, sediment archives, dated as Late Holocene, revealed scope for decoding the signatures of hydrological and geological processes associated with the monsoon vicissitudes.

Signatures of monsoon variability preserved in the Late Quaternary sediments of southwestern India have been decoded and addressed using biological proxies along with geochronological data. Barring sediments beyond the threshold for conventional 14C dating, Late Pleistocene sequences have been recognized both in Konkan and Kerala basins. Konkan area has only subsurface continental/lacustrine Late Pleistocene, whereas Kerala coast has mixed facies. The landscape as well as the vegetation cover has been substantially modified and the fossil contents and related palaeoenvironment provided ample evidence to demonstrate the landscape and vegetation dynamics since Late Pleistocene. Evidence of Myristica swamps until Late Pleistocene and its subsequent replacement by riparian forest towards Late Holocene in Konkan has been a significant impact of monsoon variations on the tropical rain forests. The prevalence of such freshwater swamps and a sensitive habitat indicated that Konkan had enjoyed an extended period of rainfall due to the combined effects of both SW and NE monsoons until the Late Pleistocene. The tropical rainforest cover along Kerala coast has shrunken considerably and pieces of evidence suggest that the entire terrain west of Sahyadri (Western Ghats) was under dense forest cover during the Holocene Climatic Optimum (9.0–6.0 k yrs BP) when the region had witnessed heavy precipitation much higher than that of the present. The forest land has been converted into major wetlands and present ecology is unsuitable to support evergreen forests and it can be concluded that coastal plains and associated landforms were covered by thick tropical evergreen forests which got destroyed by flooding towards Middle Holocene. Development of a chain of wetland system all along Kerala coast, loss of sheltered habitat and mangrove cover, and loss of sensitive freshwater Myristica swamps are some of the significant aspects brought in while addressing the monsoon variability in southwestern India.

Cyanobacteria and thecamoebians are the two major constituents of Non Pollen Palynomorphs (NPP) found in the palynological preparations. The former is well represented in the sediment archives while the latter has restricted occurrence in the Holocene sequence apart from the conventional organic matter of pollen and spores. Well preserved morphotypes of Gleotrichia and Rivularia are the best forms of cyanobacteria found in almost all the studied profiles and their abundance towards Early to Middle Holocene coincides with the heavy rainfall and wet climate conditions during the Holocene climate optimum (HCO). Contrary to cyanobacterial diversity, thecamoebians are restricted to Late Holocene in most of the studied profiles and their occurrence is correlated with the prevailing dry and stressful environmental conditions. The major elements of thecamoebians identified belong to Arcellaceans, Centropyxids and Cucurbitella types. Abundance of Centropyxids and Arcellaceans in Varapuzha, West Kadungallur, Koonamavu, Pachcha and Ernakulam indicates low humidity and low precipitation. However, the relative abundance of Centropyxids in Mid Holocene at Ernakulam and Koonamavu reflects the early colonization of this type competing with the cyanobacteria, whereas, Arcellaceans are essentially confined to Late Holocene. Dominance of cyanobacteria and its proliferation is directly related to freshwater influx of the rainfall as well as the local hydrological regimes associated with the active aquifers controlled by the geomorphological features of the region in which the wetland system sustained. Considering the signatures of cyanobacteria and thecamoebians observed in the sediment archives their occurrence in the wetlands during the Holocene corresponds to the hydrodynamic regimes brought in by the freshwater influx as a result of monsoon variability. The well preserved cyanobacterial signatures in sediment archives of Kerala coast and their scarcity or even absence elsewhere along the west coast of India indicates that they are exclusively adapted to the wetland habitats where the hydrodynamic regimes are regularly controlled by fresh water influx in the form of extended rainy days of the monsoon system.

The southern Kerala coast in SW India has experienced dramatic changes in climate and sea level during Holocene. These changes are apparently well preserved in the sedimentary archives of the estuarine basins that are entrenched on the uplifted Neogene deposits. Here we report the sedimentary processes, palaeoclimate and sea level records decoded from two borehole cores – Puthenthuruthu and Munrothuruthu borehole cores – retrieved respectively from the marine and fluvial ends of the second largest estuarine basin in SW India, the Ashtamudi estuary, using sedimentology, palynology and stable isotopes as the major proxies. The heavy rainfall event at the latter half of Early Holocene (6117 ± 101 BP) is reflected well in the isotopic signatures of the Puthenthuruthu borehole core. The higher level of lighter isotopes of oxygen and carbon at 10–15 m below ground level is a clear indication of freshwater influx from the hinterland due to intensified monsoon activity. This, in turn, was responsible for the development of Bay Head Delta in the fluvial end of the estuary during Early–Middle Holocene period. Palynological contents below the level indicate a facies change as freshwater and terrestrial elements dominate over marine contents. Further, the occurrence of desmids shows the marine facies is being gradually replaced by freshwater to continental facies. This was followed by the deposition of littoral sands as Flood Tide Islands within the estuarine basin. The palynological investigations of sediments with radiocarbon age of 4350 ± 90 BP in the Munrothuruthu borehole core show a dry phase with high saline depositional environment in the beginning which is followed by influx of freshwater as indicated by the higher content of lighter isotopes of carbon and oxygen in the calcareous nodules (algal pisolites) embedded in the sediments. The occurrence of pteridophytic spores and a few pollen of Cullenia in the palynological preparations in the upper half of the silt and clay dominated intervening layers reiterate this view.

The fossil flora recovered from the Kangvai well, Ratnagiri District, Maharashtra (17°53′41″ N; 73°12′23″ E) has been used to reconstruct the monsoon variations and seasonal rainfall pattern during the Late Pleistocene (44,020 ± 390 years BP) by using the Coexistence Approach. The reconstruction suggests that the Southwest (SW) and Northeast monsoons (NE) contributed ~ 64% and 18% of the total rainfall, respectively. Moreover, the pre-monsoon showers were responsible for about 15% of the annual rainfall. As both SW and NE monsoons were very active, along with the pre-monsoonal rainfall, the length of rainy season increased and extended up to 9 months in a year favouring the evergreen continuum and prevalence of wet evergreen forests until the Late Glacial Maximum or slightly prior to it. However, due to the weakening of NE and pre-monsoon rainfall later in the Late Pleistocene and Early Holocene, the area experiences only four months of rainy season now on account of the present-day SW monsoon. These changes resulted in the extinction of wet evergreen taxa which are now endemic to the wetter parts of Western Ghats, from the fossil locality. Our reconstruction agrees with the previous studies from the Western Ghats suggesting that the wet evergreen taxa require

Holocene climate and sea level changes have significant bearing on the geomorphic evolution of the coastal environments. A better understanding of the chronologic events of these changes is essential not only for ensuring accuracy of the climate/sea level prediction systems developed essentially from instrumental measurements but is also important for planning developmental initiatives in coastal and near shore environments. The present study is confined to the sedimentological, palynological and stable isotopic (δ 13 C and δ 15 N) evidence of palaeoclimate and sea level records in the Holocene sedimentary archives of the coastal lowlands of Periyar – Chalakudy river systems of Central Kerala, which host one of the fast developing urban – industrial centres in south India, Kochi City. The Holocene deposit in the study area is composed mainly of sand and clay dominant sediments that fall within an age range between 5390 ± 140 yrs BP and 10,110 ± 80 yrs BP. The palynological and non - pollen palynomorphs in the sediments together with the textural and geochemical attributes indicate that Holocene sedimentation took place in the area under fluctuating environmental conditions with marked changes of climate and sea level. The northern part of the study area near Pattanam revealed multiple lines of evidence of human habitation which were subsequently buried under fluvio-marine sediments in the Late Holocene.

Pollen signatures, palaeobotanical data and offshore peat indicated that the west coast of India harbored an excellent cover of mangroves until the Neogene. However, the mangrove area has shrunken considerably since then, and it is now confined largely to river mouths and tidal creeks of Kerala–Konkan basin. Sea levels and geomorphologic modifications along with climate variability have brought significant changes in the hydrological regimes which in turn have altered the habitat of the mangroves considerably. Evolution of the coastal landforms, especially the modification of the wetlands and loss of sheltered bays, has affected the mangrove habitats to a greater extent that eventually led to displacement of certain core mangrove taxa. The palynological and chronological data revealed that the mangroves of southern west coast are essentially of Middle Holocene age (7220–3880 yrs BP). Such mangrove development seems to be of global significance, as Mid-Holocene establishment of mangroves has been well recorded elsewhere when sea level stabilized. Stability of mangrove development coincides with the Holocene climate optimum (HCO) when Monsoon Asia witnessed heavy precipitation. However, the mangroves responded to environmental changes due to freshwater influx controlled by monsoon rainfall and sea level changes, leading to change in species composition as revealed by their pollen signatures. The decline of mangroves since 3500 yrs BP and further degradation except at a few sites have been attributed to the prevailing arid climate and weakening of monsoon until 1500 yrs BP. Mangrove development and sustenance in fringe areas of West Kallada along the Kerala coast may be due to local hydrological regime, with steady flow of fresh water and gradual development of deltaic conditions. As such, this area has excellent potential for the rehabilitation of mangroves. Human activity resulted in probable environmental stress for mangrove cover along the North Konkan coast, while the positive trend in emergence of mangroves in the least disturbed areas of South Konkan may be attributed to strengthening of summer monsoon in the recent past.

The palaeobotanical and palynological data along with physical proxies obtained from Konkan, western India, have been addressed while ascertaining the vegetation response to monsoon variations since Late Pleistocene (∼53,000 yrs BP). The retrieved plant fossil assemblage, being a sensitive indicator of climate changes, has important implications in palaeoclimate study of the Late Pleistocene as it is the first of its kind in the entire 7500 km long coastline of India. The plant fossil assemblage of the lacustrine sediments forms potential evidence for the prevalence of wet evergreen forest in the Late Pleistocene (∼44,000 yrs BP). This scenario was attributed to prevalence of an extended period of rainfall of both the Southwest (SW) and Northeast (NE) monsoon in Konkan, although the Indian subcontinent was under the influence of active tectonic processes. Numerous fossil plant taxa are now confined to freshwater Myristica swamps of Southeast Asia in general and that of southwestern India in particular suggesting that these areas maintain a similar monsoon trend to that existing prior to 44,000 yrs BP. On the other hand, the NE monsoon did not reappear during the Early Holocene, when the SW monsoon became strong along the Konkan coast. Many of the plant species of the fossil assemblage have been displaced from Konkan as a response to weakening of the monsoons since the Late Pleistocene and towards the Last Glacial Maximum (LGM). The aridity/reduced rainfall since Late Pleistocene, including the LGM, and limited terrestrial accumulation in the Early Holocene suggests an ecological shift and subsequent replacement of evergreen forest cover and a possible break in sedimentation. Palynological evidence of the Late Holocene (

The pollen signatures preserved in the mangrove sediments provided records of species variation over a period of time with past climate and sea level changes. The Airoli profile has a Late Pleistocene sequence, and all the other studied profiles and intervals cover the Holocene only. The absence of mangrove signatures during the Late Pleistocene interval is attributed to a relatively low sea level. The ideal conditions for mangrove development along Konkan prevailed during Middle Holocene, when the first extensive mangrove swamps appeared in Sindhudurg (Dhamapur–Hadi) area particularly between 7220 and 4770 yrs BP. This period coincides with the Holocene Climate Optimum (HCO) when Monsoon Asia witnessed much higher precipitation. However, the mangroves responded to environmental changes due to relative abundance of fresh water leading to change in species composition. Two different scenarios of mangrove response during the Late Holocene, one in Dhamapur and the other in Palm Beach, are found to be significant. The Rhizophora–Sonneratia transition from Early Mid-Holocene to Late Holocene is considered to be the most distinctive feature. The decline of mangroves since 3500 yrs BP and further degradation has been attributed to the prevailing arid climate and weakening trends of the monsoon until 1500 yrs BP. However, there seems to be a positive trend in emergence of mangroves in the least disturbed areas of south Konkan, attributed to strengthening of summer monsoon in the recent past.

Kerala coast in southwest India is endowed with an interlacing network of wetlands evolved during the Late Quaternary. The wetlands in the southern part of Kerala, especially around Kollam district, show antecedent characteristics and are incised on the Neogene sediments. These wetlands include 20.0–35.0 m thick deposits of Holocene sediments containing good archives of landform evolution and climate changes. Holocene sedimentation was initiated at about 8920 ± 110 BP and is represented mainly by sub-fossil wood/peat or carbonaceous clays. Subsequent deposition of brackish water to marine sediments occurred in the Middle Holocene. The proposed evolutionary model reveals that many wetland bodies including Sasthamkotta Lake, Chelupola Lake, Chittumalachira Lake and Kotta Lake were evolved from the proto-estuarine basins. The upper arms of the pre-Holocene Ashtamudi and Paravur estuaries were cut off due to progradation of alluvial sediments during the Holocene Climatic Optimum.

Sedimentological and palynological analysis of two borehole samples collected from the confluence of Kallada River with the Ashtamudi lake in the south west coast of India have been addressed while ascertaining the late quaternary evolution. Of the two borehole samples, the one collected from Pangod (9°03′N–76°42′E) reveals a fining upward sequence with medium to coarse sand (3.05 m) at base, organic carbon rich, silt and fine sand dominated sediments (2 m) at the middle and yellowish brown, muddy sediments (3.2 m) at the top. The middle layer embeds a suite of partly carbonized, sub-fossil logs of wet evergreen to semi-evergreen vegetation. The palynoflora of this layer reveals that the depositional site is within the tidal limit and deposition occurred under high precipitation and atmospheric humidity. The similarity in 14 C dates of a wood at 5 m bgl (7490 ± 90 yrs BP) and the embedding sediments (7480 ± 80 yrs BP) indicate quick burial of the riparian vegetation. The West Kallada borehole (9°30′N–76°37′E) reveals Middle to Late Holocene sequence of clayey silt (6250 ± 110 yrs BP–3880 ± 80 yrs BP) and sand resting unconformably over greyish white, clayey sand with pebbles and granules derived from laterite provenance. Palynological analysis shows that the Holocene sedimentation took place under marine/nearly marine environment and later changed to brackish water and finally to freshwater environment. Marine transgression ∼6000 yrs BP coupled with heavy rainfall in the hinterlands was responsible for faster sedimentation in the region. The heavy mineral contents, especially opaques, garnet and sillimanite in the sediment samples of the study area as well as the bathymetric configuration of the Ashtamudi, Sasthamkotta and Chelupola lakes reiterate the fact that these lakes have been evolved from an embayment consequent to incomplete/partial silting up during Early to Middle Holocene higher sea levels and also under high rainfall of the Holocene climatic optimum of around 10,000–7000 yrs BP.

Cyanobacteria tolerate extreme hydrological regimes, and their mucilaginous filaments account for binding and preservation of delicate structures. As the hydrological set-up is controlled by rainfall, they serve as biomarkers to distinguish palaeoenvironmental scenario and ecological shifts ranging from Late Pleistocene to Early Holocene (40 ka–2.5 ka) in the studied boreholes of the South Kerala Basin (Ayiramthengu, Panavally and West Kallada). The accrued cyanobacteria microflora is unique, as it has different morphotypes of Rivularia sp. and Gloeotrichia sp. at varying levels in the sediment profiles, probably reflecting the signatures of hydrological modifications associated with the development of wetland system. The response of cyanobacteria is similar in Panavally and Ayiramthengu from Early to Late Holocene with short signals of pauses probably relating to aberrations in precipitation. However, the Late Pleistocene and Late Holocene periods show a poor record of cyanobacteria reflecting decline in rainfall and prevalence of long spell of dry phase. From Early Holocene to Middle Holocene, the turnover of cyanobacteria has been prolific, which may be due to the Holocene Optimum rainfall. Relatively larger size and better carbonised and smaller size and lighter coloured morphotypes are correlated with such hydrological modifications as a result of high and low rainfall respectively during the Early Holocene and Late Holocene. As the cyanobacteria have the potential for adaptation and stabilization of numerous specialized eco- and morphotypes in time and space, they provided additional palaeodata as good biomarkers of climatic change.

The present paper reports on palynology and pollination ecology of eight taxa of Amorphophallus from North Western Ghats (NWGS) and Konkan region of India. Out of ten known pollen exine ornamentations of the genus, six are represented – psilate, striate, fossulate, verrucate, scabrate and the new type ‘pseudofossulate’ of Amorphophallus commutatus var. wayanadensis. These diverse pollen exine ornamentations can be utilized as an important taxonomic tool to distinguish taxa and also to resolve taxonomic problems (A. commutatus complex). The pollen of all eight taxa had retained their sculptured surface (exine ornamenatation type) after acetolysis. This clearly demonstrates that these taxa do not show susceptibility to the conventional acetolysis technique as reported earlier. The present study also highlights the importance of pollen surface morphology concerning phytogeography of the genus. Observation of pollination ecology of the studied Amorphophallus taxa reveals that all are mostly visited by beetles (Bostrichidae, Cetoniidae, Hybosoridae, Lyctidae, Nitidulidae, Rutelinae, Scarabaeidae, Staphylinidae), followed by flies (Drosophilidae, Muscidae), bees (Apidae: Trigone), ants (Formicidae, Dolichoderinae) and cockroaches (Blaberidae/Panesthiinae). The beetle families Bostrichidae, Lyctidae and Rutelinae, ant families Formicidae and Dolichoderinae and the cockroach family Blaberidae/Panesthiinae are for the first time reported as visitors in the genus Amorphophallus. Most of the taxa display features characteristic of cantharophily (beetle pollination) except A. commutatus var. commutatus and A. commutatus var. wayanadensis, where Trigona bees are the actual pollinators. The beetles (Cetoniidae, Nitidulidae, Scarabaeidae) and bees (Apidae: Trigona) are the real pollinators for the Amorphophallus species of NWGS and Konkan while rest of the insects are mere visitors for alimentary/food resources (staminode flowers, stigmatic fluid, pollen, appendix surface, appendix exudates) and using the inflorescences as mating and egg laying sites. Species belonging to the section Rhaphiophallus (Amorphophallus konkanensis and Amorphophallus sylvaticus) are pollinated by Epuraea – Haptoncurina sp. (Nitidulidae) beetles only. Generally, the species of Amorphophallus in NWGS and Konkan region with short flowering peduncle are always pollinated by dung beetles or scarabs while species bearing a long flowering peduncle are usually pollinated by Epuraea – Haptoncurina sp. (Nitidulidae) beetles and Trigona bees. Based on the comparative observations, five different phases of insect trapping in Amorphophallus taxa are characterized, focusing on the intricacies of pollination strategies of various pollinators.

Taxonomic and palynological studies on Arisaema Martius (Araceae) from the Western Ghats, India, distinguish two taxa belonging to section Tortuosa Engler. Arisaema sahyadricum S. R. Yadav, K. S. Patil & Bachulkar var. ghaticum Sardesai, S. P. Gaikwad & S. R. Yadav, a recently described variety in 2006, is treated here at the species level as A. ghaticum Punekar & Kumaran. Arisaema sivadasanii S. R. Yadav, K. S. Patil & Janarthanam, previously considered as a synonym of A. tortuosum (Wallich) Schott, is recognized here as the subspecies A. tortuosum subsp. sivadasanii (S. R. Yadav, K. S. Patil & Janarthanam) Punekar & Kumaran. Taxonomic implications are discussed and a key to the Arisaema taxa of the North Western Ghats is provided.

The organic deposits derived from the mangrove swamps form reliable stratigraphic markers within the Late Quaternary sequence of Kerala–Konkan Basin. Three generations of such deposits have been identified. The older one is dated to around 43,000–40,000 14C yr B.P., with a few dates beyond the range of radiocarbon. The younger ones date from the Middle Holocene to latest Pleistocene (10,760–4540 14C yr B.P.) and the Late Holocene (14C yr B.P.). Pollen analyses confirm that the deposits are mostly derived from the mangrove vegetation. Peat accumulation during the period 40,000–28,000 14C yr B.P. can be correlated with the excess rainfall, 40–100% greater than modern values, of the Asian summer monsoon. The low occurrence of mangrove between 22,000 and 18,000 14C yr B.P. can be attributed to the prevailing aridity and/or reduced precipitation associated worldwide with Last Glacial Maximum, because exposure surfaces and ferruginous layers are commonly found in intervals representing this period. The high rainfall of 11,000–4000 14C yr B.P. is found to be the most significant as the mangrove reached an optimum growth around 11,000 14C yr B.P. but with periods of punctuated weaker monsoons. From the present and previous studies, it has been observed that after about 5000 or 4000 14C yr B.P., the monsoons became gradually reduced leading to drying up of many of the marginal marine mangrove ecosystems. A case study of Hadi profile provided an insight to the relevance of magnetic susceptibility (χ) to record the ecological shift in Late Holocene.

The authors report a reconstruction of the palaeogeography around the Harappan town of Lothal, major port of the Indus civilisation, using multispectral satellite imagery and environmental analysis. Key results include the identification of a broad tidally influenced palaeochannel adjoining the western part of Lothal and a former estuary towards the east. Micropalaeontological analyses show that Lothal developed over a tidal salt marsh and was subsequently left high and dry as the sea level dropped.

Acrostichum intertrappeum sp. nov., a permineralized aerial stem with helically arranged petioles and roots in organic connection, is described from the Deccan Intertrappean beds of Nawargaon, District Wardha, Maharashtra, India and forms the first and the oldest record of its kind. The stem is covered with a thick ramentum of large multicellular scales and is characterized by a three angled dictyostele enclosing a few medullary bundles. The petioles are helically arranged and the vascular morphology is distinct with abaxial horseshoe-shaped ring, adaxial linear row and central dorso-ventrally elongated ring. The roots have hexarch steles and aerenchymatous cortex with large air cavities in rings. Occurrence of Acrostichum along with coastal palms, mangroves and marsh plants described earlier from this region and nearby locations suggests the north-western shore of the Deccan was linked to the equatorial ocean (South Western Tethys Sea) probably through the Narmada Valley during the deposition of Intertrappean sediments. Morphological features and anatomical characters of the fossil reveal that Acrostichum grew in marsh swamp environment or on mud flats of back water areas of the coastal environment prevailing a tropical humid climate when the Deccan region was almost at an equatorial position during the Late Cretaceous period. This new record further adds to a growing body of data on the diversification of polypodiaceous ferns that point to a much earlier crown group radiation of the group than previously thought.

Permineralized material of Acrostichum , a fern that, at present, is characteristic of brackish parts of tropical mangrove swamps, has been found in the Deccan Intertrappean cherts of Late Cretaceous age in Nawargaon, Wardha District, Maharashtra, India. The occurrence is significant as it is the oldest and also the first pre-Cenozoic macrofossil record of the genus. Being primarily a coastal plant, its presence in the Intertrappean flora has palaeoecological and phytogeographical implications because the Deccan basalt province of northwest India was linked to the equatorial ocean of southwestern Tethys during the Late Cretaceous.

Mangrove vegetation is an important component of the coastal ecosystem and is associated with near-shore marine habitat in the tropics and subtropics of the world. Indian mangrove vegetation covers about 6749 km2 along the 7516 km long coast line, including Island territories (Mandal and Naskar, 2008). The distribution of mangrove areas along the Indian coast is influenced by physical forces such as geomorphology, climate, tidal amplitude and duration and quantity of freshwater inflow (Selvam, 2003). In fact, the geomorphic setting of the mangroves of east coast of India is different from that of the west coast (Ahmed, 1972). The coastal strip of west coast is narrow, and steep in slope as compared to the gentle slope of east coast. Though there are large number of small rivers bringing enormous quantity of sediment to the Arabian Sea along the west coast, deltas are not developed, possibly due to the high-energy conditions of the coast. This topographic set up gives a contrasting pattern of mangrove vegetation in India. Accordingly, the mangrove wetlands of west coast are small, less diverse and less complicated in tidal creek network, while the east coast has larger mangrove wetlands with high species diversity. Besides, beach morphological changes along the west coast are controlled by the southwest monsoon. Therefore it is interesting to ascertain the consequences of mangroves in response to climate changes along the Kerala coast, southwestern India using the sedimentary archives of the coastal plains.

The Holocene epoch, all over the world, has witnessed exceptional climate and sea level changes. Although the south-west coast of India has a fairly thick deposit of Holocene sediments of 50-60 m in the South Kerala Sedimentary Basin (SKSB) and its adjoining coastal lowlands (see inset in Fig. 13.1), not much focus has been given to unfold its palaeo-climatic and palaeo-environmental potential till the beginning of the present century (Joseph and Thrivikramji, 2002; Nair and Padmalal, 2003; Nair et al., 2006; Kumaran et al., 2005; Limaye et al., 2007). South-west coast of India was affected significantly by sea level and climate changes which in turn had a strong bearing on human settlements/migration in the area. Recent advances in archaeological investigations in the Pattanam-Kodungallur stretch in Central Kerala (Shajan et al., 2004; Abraham, 2006) gave indications of shifts in human settlements in accordance with changing climates and/or sea level positions.

Malpophyllum is proposed as an avowed substitute name for Palmophyllum Conwentz, 1886 (non Kutzing, 1845). Three new combinations, M. succineum, M. dakshinense and M. mohgaonense , are proposed for the earlier species.

The paper is a review of the more important published data on the Mesozoic and Cenozoic plant life of Nigeria from outcrops and boreholes. The data include both procaryotic and eucaryotic organisms. The procaryotic life is represented in stromatolites of blue-green algal origin belonging to Schizothrix and Scytonema recorded in limestones from the Mfamosing quarry, 30 km northeast of Calabar. The eucaryotic life includes unicellular organisms belonging to Pyrrophyta and multicellular organisms of green and red algae, pteridophytes, gymnosperms and angiosperms of the Trachaeophytes recorded in strata of Cretaceous and Tertiary ages from different parts of Nigeria. These are represented by their secretory products — amber of some conifers, leaves, woods or disseminules. The Tertiary sequence of the Niger Delta has been divided into 8 pollen zones and 28 pollen sub-zones, whose ages are well established and which are used in differentiating the continental, paralic and marine environments of the sediments in which they occur.

Fossil plant remains collected from the Pariwar Formation, exposed about 1 km east of Habur Village, are described here. The floral assemblage at Habur is dominated by a new species of Pachypteris (P. haburensis). Besides, the assemblage comprises a fertile species of Gleichenia, Pachypteris sp., Taeniopteris spatulata McClelland, Ginkgo sp., Elatocladus tenerrima (Feistmantel) Sahni, Pagiophyllum spp., Araucarites sp. cf. A. cutchensis Feistmantel, Coniferocaulon rajmahalense Gupta and a ‘flower-like organ.