Mounts Bay Research Articles

Quantifying decadal volumetric changes along sandy beaches using improved historical aerial photographic models and contemporary data

AbstractTechnological advances have reinvigorated the aerial photogrammetric technique using both historical and contemporary imagery, and fostered new perspectives in geomorphology studies. On sandy beaches, however, the dynamic processes, the lack of tonal contrast and reduced texture, make the application of photogrammetry extremely more difficult than in most other landscapes. This study quantifies decadal volumetric changes along the beaches of the Great Ocean Road, Australia, using improved digital surface models (DSMs) derived from structure‐from‐motion (SfM) photogrammetry applied to historical archives and a contemporary unmanned aerial vehicle survey. Alongside surficial sediment analysis, this approach demonstrates the potential to relate present‐day to historical morphological changes at sandy beaches worldwide. The discussion highlights the influence of photographic scale, lens distortions, ground control points in segmented blocks, and the use of shoreline as a proxy of volumetric change. DSMs were derived using datasets obtained in 1946, 1966, 1971, 1977, 1986 and 2019, and compared to a 2007 light detection and ranging (LiDAR)‐derived DSM. The emerging approach produced suitable DSMs for volumetric analysis, except for the 1946 dataset, which had the smallest scale and was significantly vertically offset. Volumetric losses of up to 60 m3/m of beach length were calculated for parts of Mounts Bay between 1977 and 2007, and up to 21 m3/m in recent years. At Apollo Bay, the construction of the port in the early 1950s significantly impacted the natural longshore drift to the beach. The adjacent stretch of coastline accreted at a rate of ~35 m3/m between 1966 and 2007, as a function of dredge disposal and changes in sediment transport, whereas a maximum volumetric loss of ~47 m3/m was detected further north between 1977 and 2007. A volume of ~71,330 ± 15,200 m3 was lost from the system from 2007 to 2019, despite the continued deposition along the northern section of the beach.

UK meteotsunamis: a revision and update on events and their frequency

<scp>UK</scp> meteotsunamis: a revision and update on events and their frequency

Ocean Wanderers: Extralimital Encounters with Bowhead Whales (Balaena mysticetus) in Temperate European Shallow Waters

Reports of bowhead whales (Balaena mysticetus) outside the Arctic Circle are scarce. On 15 May 2016, a juvenile bowhead whale was recorded in shallow water in Mount's Bay (Cornwall, UK) much further south than the species' normal dis- tribution. Fifteen months earlier, another such sighting was made involving a juvenile bowhead whale in the shallow water of an offshore island, St Martin's (Isles of Scilly, Cornwall), only 60 km from Mount's Bay. Other observations of suspected/confirmed immature bowhead whales include (1) an unconfirmed sighting involving a whale without a dorsal fin off Cornwall (13 May 2016), (2) a confirmed sighting off France (10 May 2016), and (3) a confirmed sighting in Carlingford Lough (border of Northern Ireland/ Republic of Ireland; 29 May 2016). These extra- limital encounters present the first confirmed sightings of bowhead whales within temperate European waters. Apart from the whale sighted in 2015, the sightings in 2016 probably all involve the same juvenile whale. Indeed, photographs depicting natural scars/marks suggest that the Carlingford Lough bowhead whale is the same individual as the Mount's Bay. The whale was displaying behaviour indicative of ram feeding in a sheltered, shallow bay (< 10 m water depth). Do these records present vagrant animals from nearby endangered Arctic stocks? Whatever trig- gered these immature bowhead whales to venture well outside the Arctic Circle remains unknown, yet these observations suggest an unexpected adaptability to foraging in temperate shallow waters.

Where Fanny Balbuk Walked: Re-imagining Perth’s Wetlands

Where Fanny Balbuk Walked: Re-imagining Perth’s Wetlands

Sharing best practice

A three-year international partnership project at Mounts Bay School has come to an end, but as Alison Thomas discovered, its impact will last for much longer

The Devil's in the Detail: A review of Group I and III Petrographic Thin-Sections

Re-examination of 149 IPG Group I (119), Group Ia (17) and Groups III and IIA (13) axe petrographic thin-sections in a short period of time resulted in 24 sub-groups being identified, each sharing distinct petrographic features. Approximately 5% (8 thin-sections) had distinctive mineralogy, different from that of altered dolerite (greenstone), which defines these IPG Groups. All 149 thin-sections are visually compared with 73 new petrological thin-sections that were produced from 13 greenstone exposures in North and South Cornwall. The closest petrological match between axe and greenstone suggests Mounts Bay, possibly Long Rock. Mousehole and Penlee exposures may be the source of material for some of the 24 sub-groups. Two greenstone samples found in north-west Cornwall, away from known exposures, provided the closest petrographic match found between axe and rock thin-sections. This supports Keiller et al. (1941) in their assumption that IPG Group I originates from Mounts Bay, but indicates it is unlikely that a single exposure provided the material for all IPG Group I axes. Further analysis using a novel quantitative technique supports the results of the visual examination and may prove to be the basis of a future tool to be used in recording and assigning Neolithic axes to IPG Groups.

ABSTRACTS POSTER PRESENTATIONS

S OF POSTER PRESENTATIONS SOURCES OF SILVER IN THE EAST LOOE RIVER NATURAL OR ANTHROPOGENIC? C.J. Moon and B. Dickie Department of Geology, University of Leicester Both the East and West Looe Rivers have very high concentrations of silver in their lower reaches. Enhancement in silver in the West Looe river is caused by contamination from, and natural enrichment around, the disused lead mines at Herodsfoot. The source in the East Looe river is of comparable intensity but of enigmatic origin. We have traced the silver back to the storm water outfall from Liskeard where sediment values are 25 ppm Ag, 200 ppm Cu and 500 ppm Pb. The poster will present mineralogical data from the outfall to discriminate between a natural vein source and an anthropogenic origin. EXTENSIONAL COLLAPSE IN THE FOOTWALL REGION OF THE LIZARD OPHIOLITE, EASTERN MOUNTS BAY: A METAMORPHIC CORE-COMPLEX ANALOGUE? A.J. Styles, A.C. Alexander, R.K. Shail and R.E. Holdsworth Department of Geological Sciences, University of Durham Camborne School of Mines, University of Exeter Detailed structural field-mapping along the Mounts Bay coastalsection has revealed a group of late-Variscan extensional structures which have, until recently, largely been overlooked by previous workers. Although the extensional style is variable and partitioned, it is likely that they represent broadly coeval deformation which is related to gravity collapse. • Structures verge down the dip of pre-existing regional foliations. • They are dominated by low-angle detachments or shear zones in which the sense of displacement is consistently directed top to the south-east, which show local cross-cutting relationships with ductile features. • The low-angle detachments are associated with a suite of folds and domino faults which do not show overprinting relationships and hence suggest synchronous brittle and quasi-ductile behaviour causing strain hardening. • The late ductile deformation is cut by granite sheets, making it pre-final emplacement in age. • They are cut by moderate to steep post-orogenic normal-faults. • Many stages of quartz and, more rarely, calcite veins are observed, indicating high pore-fluid pressure throughout orogenesis. The features documented along the section form a distinct and continuous group which shows increasingly brittle deformation styles towards the south-east. There are also strong geometric similarities between these structures and soft-sediment slump and slide features, suggesting that in bulk rheological terms, the overthickened crust is acting as a viscous wedge spreading under the influence of gravity. The extensional structures appear to systematically become more brittle away from the Tregonning-Godolphin Granite and towards the Lizard Ophiolite. Kinematic indicators suggest extensional collapse directed away from a ductile region, through a zone of ductile folds, shears and transposing cleavages, and into a region deforming through brittle faulting. The ductile structure in the northwest transposes all earlier structures, but as the extension becomes more brittle to the southeast, earlier compressional features are still preserved. The ductile-brittle transition appears to be analagous to the core, carapace and cover of core complex models. Early brittle extension estimates

The lithostratigraphy and biostratigraphy of a holocene coastal sediment sequence in Marazion Marsh, west Cornwall, U.K. with reference to relative sea-level movements

A Holocene sedimentary sequence at Marazion Marsh, Mount's Bay, west Cornwall, U.K. is examined with reference to coastal evolution and relative sea-level change. A sample core analyzed in this paper shows the base of the sedimentary sequence rests on weathered bedrock material. Basal organic-rich deposits are overlain by minerogenic materials dominated by sand. A sharp contact separates these two sedimentary units. Changing coastal conditions are reconstructed using lithostratigraphic, biostratigraphic and Chronometric data from this sequence. The lower organic-rich unit accumulated between ca. 5420 ± 60 and 4380 ± 55 yrs B.P. Substantial changes in the marsh environment, involving vegetation succession from initial herb domination to mesophytic woodland and eventually to fen-carr/reed-marsh development, is indicated by pollen records from this unit. Diatom data show increased salinity within the basal sequence as arboreal pollen values decline and fen-carr/reed-marsh becomes established. Radiocarbon dates from this and other cores from west Cornwall are used to construct a local time/altitude plot of relative sea level (RSL). It is concluded that the sediment sequence at Marazion Marsh appears to have accumulated in an embayed environment. The sequence was both indirectly and directly affected by changes in relative sea-level position and the influence of protective/transgressive coastal morpho-sedimentary structures and associated processes of sedimentation during the mid-Holocene period.

The first record of the short-beaked garfish Belone svetovidovi (Belonidae) in british waters

The capture of the short-beaked garfish,Belone svetovidovi Collette &amp; Parin 1970, off the Cornish coast is of particular interest in that it represents an easterly extension to the known range of this species in the eastern North Atlantic, and the first record in British waters.In August 1990 seven garfish were angled, on mackerel bait, in Mount's Bay, Cornwall. The captor, Mr A.C. Cass, believing the garfish to be different from the common garfish,Belone belone (L.), sent the largest one to the laboratory of the Marine Biological Association for identification. The specimen was provisionally identified as the short-beaked garfish B. svetovidovi and later verified by one of us (A.W.). The other six specimens were not available for examination.Garfish, sometimes called needlefishes, have elongated bodies. Both upper and lower jaws are long and beak-like, with sharp teeth. They are epipelagic, feeding near the surface and are often observed leaping and skittering over the surface of the water. Only two species are recorded in the genus Belone in the north-eastern Atlantic.Belone belone (including subspecies) is commonly found off the European Atlantic coast as far north as Trondheim, Norway. It is also found in the North Sea, the southern Baltic seas, the Mediterranean and Black Sea where it is commercially exploited (Collette &amp; Parin, 1986).Belone svetovidovi has only recently been distinguished from B. belone, and consequently its abundance and distribution are less well known. It was first identified in northern European waters by Dorman (1984,1987) from southern Ireland.

The dinoflagellae bloom on the coast of south west England, August-September 1978

Towards the end of August 1978 SCUBA divers studying a rocky area in Mounts Bay noticed numbers of dead and dying fish and invertebrates in their study area. Their observations were passed on to Dr G. W. Potts (Griffiths, Dennis &amp; Potts, see below, p. 520). Samples of the sea water, which appeared to be very rich in phytoplankton, were taken but unfortunately were too poorly fixed for the identification of naked dinoflagellates. At the same time a number of reports of‘red tides’ and ‘fish kills’ in Mounts Bay were being passed to Mrs Stella Turk of Camborne.During the first 2 weeks of September 1978, high mortalities of intertidal populations of several ‘bait’ species, notably lugworms, were reported to the Plymouth Laboratory by anglers along the south coast of Cornwall. In the same period, abnormally high numbers of the red-band fish, Cepola rubescens, were caught in the trawls of the Laboratory's research vessels (Dr A. J. Southward, personal communication). In addition, some 20–30 specimens of another burrowing species, Amalosoma eddystonense, were taken in several trawls on the Looe Grounds; this was rather surprising since this large echiuran was thought to be rare in the Plymouth area (Dr P. E. Gibbs, personal communication).The author also received reports indicating that the non-photosynthetic but luminescent dinoflagellate Noctiluca scintillans (Macartney) Ehrenb. was abundant in coastal areas of the western English Channel. This organism is well known for forming slicks varying in colour from orange to blood-red (Le Févre &amp; Grail, 1970; Grail, Le FévreLehoerff &amp; Le Févre, 1971).

Mortality associated with a phytoplankton bloom off Penzance in Mounts Bay

Since May 1977 the Penzance Branch of the British Sub-Aqua Club has carried out a routine survey, as a contribution towards the Underwater Conservation Year Programme, on the fauna and flora of a sublittoral reef situated about 300 m to the south west of the Gear Reef in Penzance Bay. The reef is situated in water of about 17 m depth and is generally surrounded by firm sand with patches of Zostera. The reef itself is about 30 m long and 17 m wide at its widest point and 8 m high with vertical faces and overhangs at its northern end. The sides slope by stages to the sand at the southern end and contain many deep fissures with a large one at the northern end widening to a cave that passes through from east to west. The reef is aligned with its longitudinal axis running north-south and provides a diverse environment for a rich fauna and flora, a considerable background knowledge of which has been gained by the survey: by late August 1978 a total of over 30 dives, each of approximately one hour's duration, had been made in this area.

Mortality associated with a phytoplankton bloom off Penzance in Mounts Bay [southwest England] : Griffiths, A. B., R. Dennis and G. W. Potts, 1979. J. mar. biol. Ass. U.K., 59(2): 520–521. 7 Mounts Bay Road, Penzance, England

Mortality associated with a phytoplankton bloom off Penzance in Mounts Bay [southwest England] : Griffiths, A. B., R. Dennis and G. W. Potts, 1979. J. mar. biol. Ass. U.K., 59(2): 520–521. 7 Mounts Bay Road, Penzance, England

An assessment of the pollution of cornish coastal waters

A detailed survey of pollution was undertaken in five areas around the Cornwall coast in south-west England, at St. Austell and Mevagissey Bays, Falmouth Bay, Mounts Bay, St. Ives Bay and Portreath. The aim of the study was to establish baseline values against which subsequent changes could be detected and their importance evaluated. Three major investigations were undertaken in each area involving seawater sampling and analysis, heavy metal analysis of seaweed specimens and quantitative surveys of intertidal fauna and flora. In general, the areas studied showed few signs of being exposed to significant levels of industrial or sewage pollution.

Long Term Changes in Abundance of Eggs of the Cornish Pilchard (Sardina Pilchardus Walbaum) Off Plymouth

The inshore fishery for the pilchard in Cornish waters has existed for several hundred years, and such records as are available concerning fluctuation in catches and market conditions have been reviewed by Couch (1865), Cushing (1957) and Culley (1971). Although pilchard have been landed from Lyme Bay, from the eastern half of the Channel, and from the southern North Sea (Couch, 1865; Furnestin, 1945; Cushing, 1957; personal communications G. T. Boalch) the catches have usually been incidental to other fisheries and more sporadic than in Cornish waters. Traditionally there are three areas fished for the Cornish pilchard: on the north-west coast around St Ives; in Mounts Bay and towards the Scillies; and between the Lizard Pt and Bolt Tail in Devon (Couch, 1865; Culley, 1971). The latter region, constituting the inshore waters of south-east Cornwall and south Devon, effectively forms the eastern limits of the regular occurrence of commercial shoals. Knowledge of the breeding and life-history of the fish in this region has always been scarce and subject to much hearsay evidence (reviewed in Southward, 1963). Up to quite recently it was thought that the main spawning area lay well to the west of the entrance to the Channel, and it was not until the investigations reported by Corbin (1947,195°) a nd Cushing (1957)tnat it was conclusively shown that extensive spawning can occur within the English Channel from May to October. The relationship of the spawning in the western Channel to the other areas of spawning off the entrance to the Channel and in the northern Bay of Biscay is illustrated in a recent series of reports (Arbault &amp; Boutin, 1968; Arbault &amp; Lacroix-Boutin, 1969; Arbault &amp; Lacroix, 1971; Wallace, P. D. &amp; Pleasants, C. A., duplicated ICES meeting paper CM 1972/J: 8), and is further demonstrated by Demir &amp; Southward (1974) in discussing the results of a study of small scale seasonal changes in spawning intensity in inshore waters.

Geochemical and geophysical mineral exploration experiments in Mounts Bay, Cornwall : Tooms J.S., D. Taylor Smith, I. Nichol P. Ong and J. Wheldon, 1965. In: Submarine geology and geophysics, Colston Papers), W.F. Whittard and R. Bradshaw, editors, Butterworth, London, 17: 363–391.

Geochemical and geophysical mineral exploration experiments in Mounts Bay, Cornwall : Tooms J.S., D. Taylor Smith, I. Nichol P. Ong and J. Wheldon, 1965. In: Submarine geology and geophysics, Colston Papers), W.F. Whittard and R. Bradshaw, editors, Butterworth, London, 17: 363–391.

A preliminary investigation of long waves at Newlyn

Long waves of period greater than 1/2 min are recorded at Newlyn, Cornwall. There are two predominant types; one with a period of approximately 12 min and another with a period of 30 to 40 min. This investigation deals only with the longer-period type and is concerned with the eight instances during the period Mar. 1956 to Mar. 1957 where these longer waves exceeded 7 in. in amplitude. The occurrence of these waves appears to be associated with the passage of meteorological fronts and a reasonable correlation is found between the amplitude and the northward component of the frontal velocity whilst the duration of the wave activity appears to decrease as the easterly component of the frontal velocity increases. Various suggestions regarding the nature of these waves are considered. The evidence that they are edge waves is not very convincing and the most likely explanation appears to be that the waves are due to the oscillation of Mounts Bay as a whole, or of the north-western part of it.

A preliminary investigation of long waves at Newlyn

AbstractLong waves of period greater than 1/2 min are recorded at Newlyn, Cornwall. There are two predominant types; one with a period of approximately 12 min and another with a period of 30 to 40 min. This investigation deals only with the longer‐period type and is concerned with the eight instances during the period Mar. 1956 to Mar. 1957 where these longer waves exceeded 7 in. in amplitude.The occurrence of these waves appears to be associated with the passage of meteorological fronts and a reasonable correlation is found between the amplitude and the northward component of the frontal velocity whilst the duration of the wave activity appears to decrease as the easterly component of the frontal velocity increases.Various suggestions regarding the nature of these waves are considered. The evidence that they are edge waves is not very convincing and the most likely explanation appears to be that the waves are due to the oscillation of Mounts Bay as a whole, or of the north‐western part of it.

The Long-finned Tunny, Germo alalunga (Bonnaterre), in British Seas

MR. S. S. PICKARD has kindly supplied details and a photograph of a long-finned tunny, albacore or germon, Germo alalunga (Bonnaterre), found alive in a shallow pool at low tide at Morecambe, Lanes, on August 14, 1954. The fish measured 32 in. from snout to caudal fork, had a pectoral fin 12 in. in length and weighed 22 lb. This is only the twelfth British record of the species, the other eleven being as follows, the numbers indicating the footnote references 1–11 : (1) “Several years” prior to 1846 (Mount's Bay, Cornwall) ; (2) summer of 1846 (Mount's Bay, Cornwall); (3) March 13, 1861 (Chesil Beach, Weymouth, Dorset); (4) August 26, 1865 (mouth of River Exe, Devonshire); (5) October 25, 1897 (Silloth, Solway Firth); (6) June 1900 (off the Orkney Is.); (7) autumn 1901 (coast of Wexford); (8) August 1914 (Dugort, Achill Island, Co. Mayo); (9) November 1932 (Lochgoilhead, Firth of Clyde); (10) June 20, 1934 (Kilmun, Holy Loch, Firth of Clyde); (11) September 16, 1947 (west of Dingle, Co. Kerry).

Rock Succession and Structure in South Cornwall: a Revision. With Notes on the Central European Facies and Variscan Folding there present

The area dealt with in this paper is the coast of South Cornwall from Porthleven in Mount's Bay to Pentewan in Mevagissey Bay. It is separated by the Carrick Roads and tributary creeks into two parts, Meneage and the Roseland-Gorran country. The similarity of the rocks and problems in the two areas is recognized in the memoirs of H.M. Geological Survey (Flett and Hill 1912; Hill and MacAlister 1906; Reid 1907; Reid and Scrivenor 1906), but no detailed correlation based on local developments has been made, and the stratigraphical terms in use (“Mylor,” “Falmouth,” “Portscatho,” “Veryan,” “Manaccan” and “Grampound”) have never been satisfactorily defined, so that the geological history of Cornwall is still unexplained. The rock succession of South Cornwall begins with the altered rocks of two peninsulas (the Lizard and Dodman), of unknown age, related to one another and to the Start in South Devon by their rock types and by certain peculiar features in their boundary lines. The Lizard differs from the other two in the presence of an intrusive complex, also of unknown age, of serpentine-gabbro and granite-gneiss, described in 1912 by Sir John Flett, who regarded the serpentine as injection-foliated, and the Lizard boundary features as compatible with both dislocation and intrusion (Flett and Hill 1912, pp. 213–6, 242). In 1896, Professor Bonney had pointed to Kiberick valley, near Veryan, as a locality likely to afford crucial evidence of the age of the Lizard serpentine (1896, p. 48), and he had previously (1877)

Note on the Occurrence of Echinus esculentus above Low-tide Mark on the Cornish Coast

When collecting on the shores in the Plymouth area, while a member of the Easter Class at the Marine Biological Laboratory, Plymouth, in 1921, I was struck by the absence above low-water mark of Echinus esculentus, as contrasted with its abundance in this zone at Port Erin in the Isle of Man; for there, as Chadwick states, “it may be collected by hand on the beach, and on the ruined breakwater at low-water of spring tides.” There is no record of this species except below tide-marks in the “Plymouth Marine Invertebrate Fauna” list (Journ. Marine Biological Association, Vol. VII, 1904).In 1849 W. P. Cocks, in the Trans. Penzance Natural History and Antiquarian Society (“List of Echinodermata procured in Falmouth and Neighbourhood from 1843 to 1849”), recorded the occurrence of this species thus:—“Echinus sphœra.—Trawl refuse; common: young specimen found attached to stones, low-water mark.”Later (1887–8), in the same journal, G. F. Tregelles, in a paper on “Echinodermata of Mount's Bay,” makes the following statement of the species of the genus Echinus: “The commonest and largest is E. esculentus (Pennant) [E. sphœra Forbes], which literally swarms off this coast at all depths. It is brought in by trawlers; it is found in crab-pots, into which it climbs laboriously after bait; the seaweed gatherers obtain them in from one to two fathoms of water. The Mouse-hole fishermen call them ‘zarts,’ doubtless an old Cornish word.”