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Markes E. Johnson is the Charles L. MacMillan Professor of Natural Science, Emeritus, at Williams College in Williamstown, Massachusetts, where he taught courses in historical geology, paleontology, and stratigraphy in the Geosciences Department over a 35-year career. His undergraduate education in geology concluded with a BA degree (1971) from the University of Iowa. His advanced training in paleoecology through the Department of Geophysical Sciences at the University of Chicago culminated with a PhD degree (1977). Since 1990, Prof. Johnson has made one or two annual trips to the Baja California peninsula and Mexico’s Gulf of California to study coastal deposits related to the Pliocene Warm Period and later Pleistocene epochs when sea level and global temperatures were higher than today. Since 2009, he has remained active with studies regarding the Miocene to Pleistocene history of many North Atlantic islands, including those of the Cape Verde, Canary, Madeira, and Azores archipelagos. Prof. Johnson was the recipient of the 2011 Nelson Bushnell Prize for excellence in scholarship and teaching at Williams College.
Located on the northern coast of Santa Maria Island (Azores Archipelago, central North Atlantic), the Lagoinhas section preserves a carbonate buildup correlated with Marine Isotope Substage (MIS) 5e, the warmest interval of the Last Interglacial. The buildup is formed mainly by crustose coralline algae (CCA) identified as Spongites sp., and some subordinate crusts of Lithophyllum sp. and Neogoniolithon sp., as well as cf. Titanoderma sp.. Extant CCA buildups are not recorded in the archipelago. Herein, we describe in detail the morphological and taphonomical features of the Lagoinhas CCA buildup and interpret the environment in which it grew. Additionally, this buildup is compared with another of similar age, exposed in the Prainha-Praia do Calhau section on the island's opposite southern coast. The hydrodynamic regime appears to play a crucial role in the development of Azorean CCA buildups during the MIS 5e.
A. Cristina Rebelo; Michael W. Rasser; Ricardo S. Ramalho; Markes E. Johnson; Carlos S. Melo; Alfred Uchman; Rui Quartau; Björn Berning; Ana I. Neto; Ana Rita Mendes; Daniela Basso; Sérgio P. Ávila. Pleistocene coralline algal buildups on a mid-ocean rocky shore – Insights into the MIS 5e record of the Azores. Palaeogeography, Palaeoclimatology, Palaeoecology 2021, 579, 110598 .
AMA StyleA. Cristina Rebelo, Michael W. Rasser, Ricardo S. Ramalho, Markes E. Johnson, Carlos S. Melo, Alfred Uchman, Rui Quartau, Björn Berning, Ana I. Neto, Ana Rita Mendes, Daniela Basso, Sérgio P. Ávila. Pleistocene coralline algal buildups on a mid-ocean rocky shore – Insights into the MIS 5e record of the Azores. Palaeogeography, Palaeoclimatology, Palaeoecology. 2021; 579 ():110598.
Chicago/Turabian StyleA. Cristina Rebelo; Michael W. Rasser; Ricardo S. Ramalho; Markes E. Johnson; Carlos S. Melo; Alfred Uchman; Rui Quartau; Björn Berning; Ana I. Neto; Ana Rita Mendes; Daniela Basso; Sérgio P. Ávila. 2021. "Pleistocene coralline algal buildups on a mid-ocean rocky shore – Insights into the MIS 5e record of the Azores." Palaeogeography, Palaeoclimatology, Palaeoecology 579, no. : 110598.
This project examines the role of hurricane-strength events likely to have exceeded 119 km/h in wind speed that entered the Gulf of California from the open Pacific Ocean during Late Pleistocene and Holocene times to impact the granodiorite shoreline on Isla San Diego. Conglomerate dominated by large, ellipsoidal to subspherical boulders at the islands south end were canvassed at six stations. A total of 200 individual cobbles and boulders were systematically measured in three dimensions, providing the database for analyses of variations in clast shape and size. The project’s goal was to apply mathematical equations elaborated after Nott (2003) with subsequent refinements to estimate individual wave heights necessary to lift igneous blocks from the joint-bound and exfoliated coast on Isla San Diego. On average, wave heights on the order of 3 m are calculated as having impacted the Late Pleistocene rocky coastline on Isla San Diego during storms, although the largest boulders more than a meter in diameter are estimated to weigh two metric tons and would have required waves in excess of 10 m for extraction. Described for the first time, a fossil marine biota associated with the boulder beds confirms a littoral-to-very-shallow water setting correlated with Marine Isotope Substage 5e approximately 125,000 years ago. A narrow submarine ridge consisting, in part, of loose cobbles and boulders extends for 1.4 km to the southwest from the island’s tip, suggesting that Holocene storms continued to transport rock debris removed from the shore. The historical record of events registered on the Saffir–Simpson Hurricane Wind Scale in the Gulf of California suggests that major storms with the same intensity struck the island in earlier times.
Ginni Callahan; Markes Johnson; Rigoberto Guardado-France; Jorge Ledesma-Vázquez. Upper Pleistocene and Holocene Storm Deposits Eroded from the Granodiorite Coast on Isla San Diego (Baja California Sur, Mexico). Journal of Marine Science and Engineering 2021, 9, 555 .
AMA StyleGinni Callahan, Markes Johnson, Rigoberto Guardado-France, Jorge Ledesma-Vázquez. Upper Pleistocene and Holocene Storm Deposits Eroded from the Granodiorite Coast on Isla San Diego (Baja California Sur, Mexico). Journal of Marine Science and Engineering. 2021; 9 (5):555.
Chicago/Turabian StyleGinni Callahan; Markes Johnson; Rigoberto Guardado-France; Jorge Ledesma-Vázquez. 2021. "Upper Pleistocene and Holocene Storm Deposits Eroded from the Granodiorite Coast on Isla San Diego (Baja California Sur, Mexico)." Journal of Marine Science and Engineering 9, no. 5: 555.
Unattached nodules of calcareous red algae (Rhodophyta), known as rhodoliths, are widely reported and studied in places that extend from the tropics to polar latitudes. Factors controlling the distribution of the rhodolith-forming species remain poorly understood. A review of the global distribution of present-day rhodolith beds was undertaken, collating information on 106 rhodolith-forming species from 10 families, representing 21 genera distributed through 11 realms: 1) Arctic, 2) Temperate Northern Atlantic, 3) Temperate Northern Pacific, 4) Tropical Atlantic, 5) Western Indo-Pacific, 6) Central Indo-Pacific, 7) Eastern Indo-Pacific, 8) Tropical Eastern Pacific, 9) Temperate South America, 10) Temperate Australasia, and 11) Southern Ocean. The Central Indo-Pacific and Temperate Australasia proved to be the most diverse realms. Of 62 provinces across these realms, the Tropical Southwestern Atlantic, the Mediterranean Sea and the Tropical East Pacific feature the highest diversity of rhodolith-forming species. A significant proportion of the 106 species (14.2%; 15 species) are endemic to a single biogeographic province. Species richness is weakly related to sampling effort (r2=0.573) and unrelated to littoral area (r2=0.012). Even when high latitude provinces are excluded from the analysis, no correlation between species richness and littoral was found (r2 = 0.0005). A wider, evolutionary-time framework revealed that the existence of marine barriers and the geological age of their final emplacement are key elements to explaining compositional differences between the rhodoliths of former contiguous areas (e.g., Pacific versus Atlantic shores of Panama and Costa Rica, in the Central America; eastern Mediterranean Sea versus Red Sea and Gulf of Aden). Finally, we propose that the lower diversity of the rhodolith-forming species in the tropical Pacific Ocean when compared to the Atlantic Ocean (23 versus 33 spp.), may be linked to the higher abundance of corals and coral reefs in the Pacific, which act as competitors with coralline algae for space.
A. Cristina Rebelo; Markes E. Johnson; Michael W. Rasser; Luís Silva; Carlos S. Melo; Sérgio P. Ávila. Global biodiversity and biogeography of rhodolith-forming species. Frontiers of Biogeography 2021, 13, 1 .
AMA StyleA. Cristina Rebelo, Markes E. Johnson, Michael W. Rasser, Luís Silva, Carlos S. Melo, Sérgio P. Ávila. Global biodiversity and biogeography of rhodolith-forming species. Frontiers of Biogeography. 2021; 13 (1):1.
Chicago/Turabian StyleA. Cristina Rebelo; Markes E. Johnson; Michael W. Rasser; Luís Silva; Carlos S. Melo; Sérgio P. Ávila. 2021. "Global biodiversity and biogeography of rhodolith-forming species." Frontiers of Biogeography 13, no. 1: 1.
Pliocene body fossils from Santa Maria Island, Azores, have been studied for decades, but only more recently have ichnofossils received their due attention. Calcareous Pliocene deposits from the Baía de Nossa Senhora section contain numerous, diverse, well-preserved natural casts of invertebrate borings. The study of this type of fossils adds to knowledge on the dispersal of benthic faunas across oceans to volcanic oceanic islands. The borings belong to seven ichnogenera and twenty-two ichnotaxa at the ichnospecies level with more than half pertaining to Entobia, which is produced by clionaid sponges. Other borings found were produced by bivalves (Gastrochaenolites), polychaete worms (Caulostrepsis and Maeandropolydora), sipunculid worms (Trypanites), phoronid worms (Talpina) and ctenostome bryozoans (Iramena). The occurrence, ichnogeny, distribution and preservational state of the borings suggest that the bearing bioclasts have been exposed for several years on the sea floor. The borings derive from different bathymetric zones on the shelf, and their formation took place during several bioerosional phases. The association of borings belongs to the Entobia ichnofacies, which is typical of carbonate rocky shores, and shows close similarity to those described from the Paratethys, Mediterranean and partly the eastern Atlantic regions. This fits the idea that most of the Neogene shallow-water marine fauna in the Azores is biogeographically related to the eastern Atlantic shores.
Árpád Dávid; Alfred Uchman; Ricardo S. Ramalho; José Madeira; Carlos S. Melo; Patrícia Madeira; Ana Cristina Rebelo; Björn Berning; Markes E. Johnson; Sérgio P. Ávila. Diverse bioerosion structures in lower Pliocene deposits from a volcanic oceanic island: Baía de Nossa Senhora section, Santa Maria Island, Azores (central North Atlantic). Palaeogeography, Palaeoclimatology, Palaeoecology 2021, 569, 110284 .
AMA StyleÁrpád Dávid, Alfred Uchman, Ricardo S. Ramalho, José Madeira, Carlos S. Melo, Patrícia Madeira, Ana Cristina Rebelo, Björn Berning, Markes E. Johnson, Sérgio P. Ávila. Diverse bioerosion structures in lower Pliocene deposits from a volcanic oceanic island: Baía de Nossa Senhora section, Santa Maria Island, Azores (central North Atlantic). Palaeogeography, Palaeoclimatology, Palaeoecology. 2021; 569 ():110284.
Chicago/Turabian StyleÁrpád Dávid; Alfred Uchman; Ricardo S. Ramalho; José Madeira; Carlos S. Melo; Patrícia Madeira; Ana Cristina Rebelo; Björn Berning; Markes E. Johnson; Sérgio P. Ávila. 2021. "Diverse bioerosion structures in lower Pliocene deposits from a volcanic oceanic island: Baía de Nossa Senhora section, Santa Maria Island, Azores (central North Atlantic)." Palaeogeography, Palaeoclimatology, Palaeoecology 569, no. : 110284.
This study examines the role of North Atlantic storms degrading a Late Pleistocene rocky shoreline formed by basaltic rocks overlying hyaloclastite rocks on a small volcanic peninsula connected to Gran Canaria in the central region of the Canary Archipelago. A conglomerate dominated by large, ellipsoidal to angular boulders eroded from an adjacent basalt flow was canvassed at six stations distributed along 800 m of the modern shore at El Confital, on the outskirts of Las Palmas de Gran Canaria. A total of 166 individual basalt cobbles and boulders were systematically measured in three dimensions, providing the database for analyses of variations in clast shape and size. The goal of this study was to apply mathematical equations elaborated after Nott (2003) and subsequent refinements in order to estimate individual wave heights necessary to lift basalt blocks from the layered and joint-bound sea cliffs at El Confital. On average, wave heights in the order of 4.2 to 4.5 m are calculated as having impacted the Late Pleistocene rocky coastline at El Confital, although the largest boulders in excess of 2 m in diameter would have required larger waves for extraction. A review of the fossil marine biota associated with the boulder beds confirms a littoral to very shallow water setting correlated in time with Marine Isotope Stage 5e (Eemian Stage) approximately 125,000 years ago. The historical record of major storms in the regions of the Canary and Azorean islands indicates that events of hurricane strength were likely to have struck El Confital in earlier times. Due to its high scientific value, the outcrop area featured in this study is included in the Spanish Inventory of Geosites and must be properly protected and managed to ensure conservation against the impact of climate change foreseen in coming years.
Inés Galindo; Markes Johnson; Esther Martín-González; Carmen Romero; Juana Vegas; Carlos Melo; Sérgio Ávila; Nieves Sánchez. Late Pleistocene Boulder Slumps Eroded from a Basalt Shoreline at El Confital Beach on Gran Canaria (Canary Islands, Spain). Journal of Marine Science and Engineering 2021, 9, 138 .
AMA StyleInés Galindo, Markes Johnson, Esther Martín-González, Carmen Romero, Juana Vegas, Carlos Melo, Sérgio Ávila, Nieves Sánchez. Late Pleistocene Boulder Slumps Eroded from a Basalt Shoreline at El Confital Beach on Gran Canaria (Canary Islands, Spain). Journal of Marine Science and Engineering. 2021; 9 (2):138.
Chicago/Turabian StyleInés Galindo; Markes Johnson; Esther Martín-González; Carmen Romero; Juana Vegas; Carlos Melo; Sérgio Ávila; Nieves Sánchez. 2021. "Late Pleistocene Boulder Slumps Eroded from a Basalt Shoreline at El Confital Beach on Gran Canaria (Canary Islands, Spain)." Journal of Marine Science and Engineering 9, no. 2: 138.
The presence of decapod crustaceans in the Pliocene and Pleistocene (MIS 5e) fossil record of Santa Maria Island (Azores Archipelago) is herein reviewed. Our study raises the number of fossil decapods from this island from one species to 10 taxa (three for the Pliocene and seven for the Last Interglacial). Four of these 10 taxa are reported for the first time in the fossil record, worldwide. A new species of a mud shrimp is also described (Upogebia azorensis n. sp.). Our study suggests that the Plio–Pleistocene decapod assemblages of the Azores did not differ significantly from modern ones, being dominated by species that are today widespread across the Webbnesia ecoregion, the Mediterranean Sea, and the eastern Atlantic shores, including the Azores. As far as can be judged from the limited fossil record, apparently no tropical crab species with a Cabo Verdean/Senegalese provenance reached the Azores during windows of opportunity associated with Glacial Termination 2 or with the initial setting of the Last Interglacial period. This contribution increases the total number of marine taxa reported for the Pliocene and Pleistocene outcrops of Santa Maria Island to 218 and 155, respectively, highlighting the scientific relevance of its palaeontological heritage.
Matúš Hyžný; Carlos S. Melo; Ricardo S. Ramalho; Ricardo Cordeiro; Patrícia Madeira; Lara Baptista; A. Cristina Rebelo; Cynthia Gómez; Alfred Uchman; Markes E. Johnson; Björn Berning; Sérgio P. Ávila. Pliocene and late Pleistocene (MIS 5e) decapod crustaceans from Santa Maria Island (Azores Archipelago: Central Atlantic): systematics, palaeoecology and palaeobiogeography. Journal of Quaternary Science 2020, 36, 91 -109.
AMA StyleMatúš Hyžný, Carlos S. Melo, Ricardo S. Ramalho, Ricardo Cordeiro, Patrícia Madeira, Lara Baptista, A. Cristina Rebelo, Cynthia Gómez, Alfred Uchman, Markes E. Johnson, Björn Berning, Sérgio P. Ávila. Pliocene and late Pleistocene (MIS 5e) decapod crustaceans from Santa Maria Island (Azores Archipelago: Central Atlantic): systematics, palaeoecology and palaeobiogeography. Journal of Quaternary Science. 2020; 36 (1):91-109.
Chicago/Turabian StyleMatúš Hyžný; Carlos S. Melo; Ricardo S. Ramalho; Ricardo Cordeiro; Patrícia Madeira; Lara Baptista; A. Cristina Rebelo; Cynthia Gómez; Alfred Uchman; Markes E. Johnson; Björn Berning; Sérgio P. Ávila. 2020. "Pliocene and late Pleistocene (MIS 5e) decapod crustaceans from Santa Maria Island (Azores Archipelago: Central Atlantic): systematics, palaeoecology and palaeobiogeography." Journal of Quaternary Science 36, no. 1: 91-109.
This project examines the role of tropical storms in the northeast Atlantic Ocean related to the post-mortem deposition of rhodoliths in coastal settings during Neogene to Holocene time with primary emphasis on Sal Island in the Cabo Verde Archipelago located 600 km off the coast of Senegal in northwest Africa. Fossil rhodoliths from 10 to 15 cm in diameter are equal in size to contemporary rhodoliths that survive for a century or more at water depths undisturbed by all but the most energetic storms. The shape of large rhodoliths makes them susceptible to rare disturbances with sufficient energy to export them beyond their preferred habitat into extreme environments that include supratidal settings. The methodology of this study gauges the relative sphericity of rhodoliths based on measurements across three axes perpendicular to one another, plots size variations on bar graphs, and considers whether or not individual nodules are nucleated around rock cores eroded from proximal rocky shores. Sal Island is impacted on a steady basis by wave swell generated from the Northeast Trade Winds, but Pleistocene and Holocene deposits with large rhodoliths on the Island’s windward coast are interpreted as the result of major storms of hurricane intensity. Comparison of Sal Island rhodoliths with Pliocene and Miocene examples from other insular localities in the Northeast Atlantic considers evidence for displacement of the Inter-Tropical Convergence Zone (ITCZ) into more northern latitudes as an influence on past hurricane tracks that are less common today.
Markes Johnson; Ricardo Ramalho; Carlos Marques Da Silva. Storm-Related Rhodolith Deposits from the Upper Pleistocene and Recycled Coastal Holocene on Sal Island (Cabo Verde Archipelago). Geosciences 2020, 10, 419 .
AMA StyleMarkes Johnson, Ricardo Ramalho, Carlos Marques Da Silva. Storm-Related Rhodolith Deposits from the Upper Pleistocene and Recycled Coastal Holocene on Sal Island (Cabo Verde Archipelago). Geosciences. 2020; 10 (11):419.
Chicago/Turabian StyleMarkes Johnson; Ricardo Ramalho; Carlos Marques Da Silva. 2020. "Storm-Related Rhodolith Deposits from the Upper Pleistocene and Recycled Coastal Holocene on Sal Island (Cabo Verde Archipelago)." Geosciences 10, no. 11: 419.
This project examines the role of high-latitude storms degrading a Holocene coast formed by igneous rocks composed of low-grade chromite ore and dunite that originated within the Earth’s crust near the upper mantle. Such rocks are dense and rarely exposed at the surface by tectonic events in the reconfiguration of old ocean basins. An unconsolidated boulder beach occupies Støypet valley on Leka Island in northern Norway, formerly an open channel 10,000 years ago when glacial ice was in retreat and rebound of the land surface was about to commence. Sea cliffs exposing a stratiform ore body dissected by fractures was subject to wave erosion that shed large cobbles and small boulders into the channel. Competing mathematical equations are applied to estimate the height of storm waves impacting the channel floor and cliffs, and the results are compared with observations on wave heights generated by recent storms striking the Norwegian coast with the intensity of an orkan (Norwegian for hurricane). Lateral size variations in beach clasts suggest that Holocene storms struck Leka Island from the southwest with wave heights between 5 and 7.5 m based on the largest beach boulders. This result compares favorably with recent high-latitude storm tracks in the Norwegian Sea and their recorded wave heights. The density of low-grade chromite ore (3.32 g/cm3) sampled from the beach deposit exceeds that of rocks like limestone or other igneous rocks such as rhyolite, andesite, and basalt taken into consideration regarding coastal boulder deposits associated with classic hurricanes in more tropical settings.
Markes E. Johnson. Holocene Boulder Beach Eroded from Chromite and Dunite Sea Cliffs at Støypet on Leka Island (Northern Norway). Journal of Marine Science and Engineering 2020, 8, 644 .
AMA StyleMarkes E. Johnson. Holocene Boulder Beach Eroded from Chromite and Dunite Sea Cliffs at Støypet on Leka Island (Northern Norway). Journal of Marine Science and Engineering. 2020; 8 (9):644.
Chicago/Turabian StyleMarkes E. Johnson. 2020. "Holocene Boulder Beach Eroded from Chromite and Dunite Sea Cliffs at Støypet on Leka Island (Northern Norway)." Journal of Marine Science and Engineering 8, no. 9: 644.
The 450-m long spit that extends westward from the northwest corner of Isla San Luis Gonzaga is one of the largest and most complex constructions of unconsolidated cobbles and boulders found anywhere in Mexico’s Gulf of California. The material source derives from episodic but intense storm erosion along the island’s andesitic cliff face with steep northern exposures. A well-defined marine terrace from the late Pleistocene cuts across the same corner of the island and provides a marker for the subsequent development of the spit that post-dates tectonic-eustatic adjustments. A total of 660 individual andesite clasts from seven transects across the spit were measured for analyses of change in shape and size. These data are pertinent to the application of mathematical formulas elaborated after Nott (2003) and subsequent refinements to estimate individual wave heights necessary for lift from parent sea cliffs and subsequent traction. Although the ratio of boulders to clasts diminishes from the proximal to distal end of the structure, relatively large boulders populate all transects and the average wave height required for the release of joint-bound blocks at the rocky shore amounts to 5 m. Based on the region’s historical record of hurricanes, such storms tend to decrease in intensity as they migrate northward through the Gulf of California’s 1100-km length. However, the size and complexity of the San Luis Gonzaga spit suggests that a multitude of extreme storm events impacted the island in the upper gulf area through the Holocene time, yielding a possible average growth rate between 7 and 8 m/century over the last 10,000 years. In anticipation of future storms, a system to track the movement of sample boulders should be emplaced on the San Luis Gonzaga spit and similar localities with major coastal boulder deposits.
Rigoberto Guardado-France; Markes E. Johnson; Jorge Ledesma-Vázquez; Miguel Angel Santa Rosa del Rio; Ángel R. Herrera-Gutiérrez. Multiphase Storm Deposits Eroded from Andesite Sea Cliffs on Isla San Luis Gonzaga (Northern Gulf of California, Mexico). Journal of Marine Science and Engineering 2020, 8, 525 .
AMA StyleRigoberto Guardado-France, Markes E. Johnson, Jorge Ledesma-Vázquez, Miguel Angel Santa Rosa del Rio, Ángel R. Herrera-Gutiérrez. Multiphase Storm Deposits Eroded from Andesite Sea Cliffs on Isla San Luis Gonzaga (Northern Gulf of California, Mexico). Journal of Marine Science and Engineering. 2020; 8 (7):525.
Chicago/Turabian StyleRigoberto Guardado-France; Markes E. Johnson; Jorge Ledesma-Vázquez; Miguel Angel Santa Rosa del Rio; Ángel R. Herrera-Gutiérrez. 2020. "Multiphase Storm Deposits Eroded from Andesite Sea Cliffs on Isla San Luis Gonzaga (Northern Gulf of California, Mexico)." Journal of Marine Science and Engineering 8, no. 7: 525.
Modern and palaeo-shores from Pleistocene Marine Isotope Substage 5e (MIS 5e) featuring prominent cobble/boulder deposits from three locations, on the southern and eastern coast of Santa Maria Island in the Azores Archipelago, were compared, in order to test the idea of higher storminess during the Last Interglacial. A total of 175 basalt clasts from seven transects were measured manually in three dimensions perpendicular to one another. Boulders that exceeded the minimum definitional diameter of 25 cm contributed to 45% of the clasts, with the remainder falling into the category of large cobbles. These were sorted for variations in shape, size, and weight pertinent to the application of two mathematical formulas to estimate wave heights necessary for traction. Both equations were based on the “Nott-Approach”, one of them being sensitive to the longest axis, the other to the shortest axis. The preponderance of data derived from the Pleistocene deposits, which included an intertidal invertebrate fauna for accurate dating. The island’s east coast at Ponta do Cedro lacked a modern boulder beach due to steep rocky shores, whereas raised Pleistocene palaeo-shores along the same coast reflect surged from an average wave height of 5.6 m and 6.5 m. Direct comparison between modern and Pleistocene deposits at Ponta do Castelo to the southeast and Prainha on the island’s south shore produced contrasting results, with higher wave heights during MIS 5e at Ponta do Castelo and higher wave heights for the modern boulder beach at Prainha. Thus, our results did not yield a clear conclusion about higher storminess during the Last Interglacial compared to the present day. Historical meteorological records pit the seasonal activity of winter storms arriving from the WNW-NW against the scant record of hurricanes arriving from the ESE-SE. The disparity in the width of the marine shelf around Santa Maria Island with broad shelves to the north and narrow shelves to the south and east suggested that periodic winter storms had a more regular role in coastal erosion, whereas the rare episodic recurrence of hurricanes had a greater impact on southern and southeastern rocky shores, where the studied coastal boulder deposits were located.
Sérgio P. Ávila; Markes E. Johnson; Ana Cristina Rebelo; Lara Baptista; Carlos S. Melo. Comparison of Modern and Pleistocene (MIS 5e) Coastal Boulder Deposits from Santa Maria Island (Azores Archipelago, NE Atlantic Ocean). Journal of Marine Science and Engineering 2020, 8, 386 .
AMA StyleSérgio P. Ávila, Markes E. Johnson, Ana Cristina Rebelo, Lara Baptista, Carlos S. Melo. Comparison of Modern and Pleistocene (MIS 5e) Coastal Boulder Deposits from Santa Maria Island (Azores Archipelago, NE Atlantic Ocean). Journal of Marine Science and Engineering. 2020; 8 (6):386.
Chicago/Turabian StyleSérgio P. Ávila; Markes E. Johnson; Ana Cristina Rebelo; Lara Baptista; Carlos S. Melo. 2020. "Comparison of Modern and Pleistocene (MIS 5e) Coastal Boulder Deposits from Santa Maria Island (Azores Archipelago, NE Atlantic Ocean)." Journal of Marine Science and Engineering 8, no. 6: 386.
Sedimentary rocks are rarely preserved on reefless volcanic oceanic islands because they are mostly exported from coastal areas towards the abyssal plains and such islands typically undergo subsidence. In contrast, the exceptional geological record of the uplifted Santa Maria Island (Azores) provides a unique opportunity to gain insight on such coastal systems. This study focuses on a locality at Ponta do Cedro (eastern Santa Maria Island), which features a series of marine fossiliferous sediments wedged between steep lava deltas. As demonstrated by local structure, these sediments correspond to clinoforms deposited on the steep submarine slope of an active volcanic island, implying transport from shallow waters to greater depths and subsequent colonization by benthic communities. Rapid volcanic progradation eventually sealed the deposits, allowing for their preservation and providing a rare snapshot of the ecology during those intervals, in addition to insights on sedimentary dynamics along submarine island slopes. This study reveals spatial relationships between wedges of sedimentary bodies encapsulated by lavas in the Ponta do Cedro section, and interprets depositional processes preserved in those strata based on sedimentological and palaeontological data. The dynamics of the environment are mostly related to relative sea‐level changes, intense volcanic activity and regional uplift during the Neogene.
Alfred Uchman; Markes E. Johnson; Ricardo S. Ramalho; Rui Quartau; Björn Berning; Ana Hipólito; Carlos S. Melo; A. Cristina Rebelo; Ricardo Cordeiro; Sérgio P. Ávila. Neogene marine sediments and biota encapsulated between lava flows on Santa Maria Island (Azores, north‐east Atlantic): An interplay between sedimentary, erosional and volcanic processes. Sedimentology 2020, 67, 3595 -3618.
AMA StyleAlfred Uchman, Markes E. Johnson, Ricardo S. Ramalho, Rui Quartau, Björn Berning, Ana Hipólito, Carlos S. Melo, A. Cristina Rebelo, Ricardo Cordeiro, Sérgio P. Ávila. Neogene marine sediments and biota encapsulated between lava flows on Santa Maria Island (Azores, north‐east Atlantic): An interplay between sedimentary, erosional and volcanic processes. Sedimentology. 2020; 67 (7):3595-3618.
Chicago/Turabian StyleAlfred Uchman; Markes E. Johnson; Ricardo S. Ramalho; Rui Quartau; Björn Berning; Ana Hipólito; Carlos S. Melo; A. Cristina Rebelo; Ricardo Cordeiro; Sérgio P. Ávila. 2020. "Neogene marine sediments and biota encapsulated between lava flows on Santa Maria Island (Azores, north‐east Atlantic): An interplay between sedimentary, erosional and volcanic processes." Sedimentology 67, no. 7: 3595-3618.
Previous studies on the role of hurricanes in Mexico’s Gulf of California examined coastal boulder deposits (CBDs) eroded from limestone and rhyolite sea cliffs. Sedimentary and volcanic in origin, these lithotypes are less extensively expressed as rocky shores than others in the overall distribution of gulf shores. Andesite that accumulated as serial volcanic flows during the Miocene constitutes by far the region’s most pervasive rocky shores. Here, we define a subgroup of structures called barrier boulder deposits (BBDs) that close off lagoons as a result of lateral transport from adjacent rocky shores subject to recurrent storm erosion. Hidden Harbor (Puerto Escondido) is the most famous natural harbor in all of Baja California. Accessed from a single narrow entrance, it is commodious in size (2.3 km2) and fully sheltered by outer andesite hills linked by two natural barriers. The average weight of embedded boulders in a succession of six samples tallied over a combined distance of 710 m ranges between 74 and 197 kg calculated on the basis of boulder volume and the specific gravity of andesite. A mathematical formula is utilized to estimate the wave height necessary to transport large boulders from their source. Average wave height interpreted by this method varies between 4.1 and 4.6 m. Input from fossil deposits and physical geology related to fault trends is applied to reconstruct coastal evolution from a more open coastal scenario during the Late Pleistocene 125,000 years ago to lagoon closure in Holocene time.
Markes E. Johnson; Erlend M. Johnson; Rigoberto Guardado-France; Jorge Ledesma-Vázquez. Holocene Hurricane Deposits Eroded as Coastal Barriers from Andesite Sea Cliffs at Puerto Escondido (Baja California Sur, Mexico). Journal of Marine Science and Engineering 2020, 8, 75 .
AMA StyleMarkes E. Johnson, Erlend M. Johnson, Rigoberto Guardado-France, Jorge Ledesma-Vázquez. Holocene Hurricane Deposits Eroded as Coastal Barriers from Andesite Sea Cliffs at Puerto Escondido (Baja California Sur, Mexico). Journal of Marine Science and Engineering. 2020; 8 (2):75.
Chicago/Turabian StyleMarkes E. Johnson; Erlend M. Johnson; Rigoberto Guardado-France; Jorge Ledesma-Vázquez. 2020. "Holocene Hurricane Deposits Eroded as Coastal Barriers from Andesite Sea Cliffs at Puerto Escondido (Baja California Sur, Mexico)." Journal of Marine Science and Engineering 8, no. 2: 75.
Site destruction and obfuscation are significant processes that hinder archaeological interpretations. This article focuses on a few natural taphonomic agencies impinging on archaeological site preservation in highland Central American settings. Precipitation and drainage are especially crucial in these riverine environments. Access to water for consumption and agriculture were vital factors in the determination of settlement patterns. Over time, a mixture of both gradual and catastrophic processes ranging from moderate rainstorms to hurricanes are known to trigger flooding, riverine erosion, and landslides with the potential to destroy or obscure vulnerable valley sites. Examples are given of Classic Period (A.D. 200–900) archaeological sites from the Cucuyagua and Sensenti valleys in western Honduras affected by catastrophic weather events during occupation and after site abandonment. Mudslides and landslides, in particular, are highlighted as significant destructive processes that remain under‐discussed in regional literature. Furthermore, we highlight the possible causal role of hurricanes in provoking both landslides and flooding. Finally, we consider the impact of these events in our particular study area.
Erlend M. Johnson; B. Gudveig Baarli; Markes E. Johnson; Pastor R. Gomez Zuñiga. Effects of hurricanes, mudslides, flooding, and riverine erosion on the erasure of archaeological sites in tropical, highland Honduras. Geoarchaeology 2019, 35, 338 -350.
AMA StyleErlend M. Johnson, B. Gudveig Baarli, Markes E. Johnson, Pastor R. Gomez Zuñiga. Effects of hurricanes, mudslides, flooding, and riverine erosion on the erasure of archaeological sites in tropical, highland Honduras. Geoarchaeology. 2019; 35 (3):338-350.
Chicago/Turabian StyleErlend M. Johnson; B. Gudveig Baarli; Markes E. Johnson; Pastor R. Gomez Zuñiga. 2019. "Effects of hurricanes, mudslides, flooding, and riverine erosion on the erasure of archaeological sites in tropical, highland Honduras." Geoarchaeology 35, no. 3: 338-350.
This work advances research on the role of hurricanes in degrading the rocky coastline within Mexico’s Gulf of California, most commonly formed by widespread igneous rocks. Under evaluation is a distinct coastal boulder bed (CBB) derived from banded rhyolite with boulders arrayed in a partial-ring configuration against one side of the headland on Ensenada Almeja (Clam Bay) north of Loreto. Preconditions related to the thickness of rhyolite flows and vertical fissures that intersect the flows at right angles along with the specific gravity of banded rhyolite delimit the size, shape and weight of boulders in the Almeja CBB. Mathematical formulae are applied to calculate the wave height generated by storm surge impacting the headland. The average weight of the 25 largest boulders from a transect nearest the bedrock source amounts to 1200 kg but only 30% of the sample is estimated to exceed a full metric ton in weight. The wave height calculated to move those boulders is close to 8 m. Additional localities with CBBs composed of layered rock types such as basalt and andesite are proposed for future studies within the Gulf of California. Comparisons with selected CBBs in other parts of the world are made.
Markes E. Johnson; Rigoberto Guardado-France; Erlend M. Johnson; Jorge Ledesma-Vázquez. Geomorphology of a Holocene Hurricane Deposit Eroded from Rhyolite Sea Cliffs on Ensenada Almeja (Baja California Sur, Mexico). Journal of Marine Science and Engineering 2019, 7, 193 .
AMA StyleMarkes E. Johnson, Rigoberto Guardado-France, Erlend M. Johnson, Jorge Ledesma-Vázquez. Geomorphology of a Holocene Hurricane Deposit Eroded from Rhyolite Sea Cliffs on Ensenada Almeja (Baja California Sur, Mexico). Journal of Marine Science and Engineering. 2019; 7 (6):193.
Chicago/Turabian StyleMarkes E. Johnson; Rigoberto Guardado-France; Erlend M. Johnson; Jorge Ledesma-Vázquez. 2019. "Geomorphology of a Holocene Hurricane Deposit Eroded from Rhyolite Sea Cliffs on Ensenada Almeja (Baja California Sur, Mexico)." Journal of Marine Science and Engineering 7, no. 6: 193.
San Basilio basin in Baja California Sur (Mexico) exhibits distinct styles of volcanism that interrupted phases of normal sedimentation correlated with the Zanclean Stage (Lower Pliocene). Sea cliffs around a 4-km2 bay opening onto the Gulf of California are dominated by rhyolite, mudstone, sandstone, and limestone. Volcanism associated with re-sedimented hyaloclastite is regionally uncommon and the goal was to investigate interactions between volcanic events and intervals of stability represented by fossil-rich strata. Methods of study involved a combination of microfossil and macrofossil analyses. Relating the basin’s faults to Pliocene development in the greater Gulf of California was a secondary goal. Microfossils Bolivina bicostata and B. interjuncta recovered from mudstone indicate an initial water column of 150 m. An abrupt hydromagmatic explosion ruptured the mudstone cover, followed by banded rhyolite flows inter-bedded with sandstone. Outlying limestone beds with the index fossil Clypeaster bowersi are separated from rhyolite by conglomerate eroded under intertidal conditions. A renewed phase of activity saw eruption of smaller volcanoes in the basin center semi-contemporaneous with pecten limestone deposited on unstable slopes. Normal faults conform to a pattern of extensional rifting in the proto-gulf, followed by cross-cutting faults indicating the onset of transtensional tectonics beginning about 3.5 Ma.
Markes E. Johnson; David H. Backus; Ana Luisa Carreño; Jorge Ledesma-Vázquez. Rhyolite Domes and Subsequent Offlap of Pliocene Carbonates on Volcanic Islets at San Basilio (Baja California Sur, Mexico). Geosciences 2019, 9, 87 .
AMA StyleMarkes E. Johnson, David H. Backus, Ana Luisa Carreño, Jorge Ledesma-Vázquez. Rhyolite Domes and Subsequent Offlap of Pliocene Carbonates on Volcanic Islets at San Basilio (Baja California Sur, Mexico). Geosciences. 2019; 9 (2):87.
Chicago/Turabian StyleMarkes E. Johnson; David H. Backus; Ana Luisa Carreño; Jorge Ledesma-Vázquez. 2019. "Rhyolite Domes and Subsequent Offlap of Pliocene Carbonates on Volcanic Islets at San Basilio (Baja California Sur, Mexico)." Geosciences 9, no. 2: 87.
Between Lagos and Albufeira, the Algarve coast of southern Portugal is marked by outcrops of the lower Miocene Lagos-Portimão Formation (LPF) consisting of yellow sandstone and coarse skeletal-rhodolithic limestone. This contribution focuses on the rhodoliths, their paleoecology, taphonomy, and biological composition, in the Lagos Biocalcarenite, the lower member of the LPF. Special attention is paid to the unusual occurrence of numerous rhodoliths nucleated around articulated bivalve shells, as well as to the nature of their biological interactions and taphonomic features. The calcareous algae of the rhodoliths (Phymatolithon calcareum and Spongites sp.) are commonly interlayered with thin bands of bryozoans and serpulids. Thick beds of non-nucleated spheroidal rhodoliths first appear at approximately 5–6 m above the base of the LPF as a result of a storm event that shifted rhodoliths in a shoreward direction. The bioeroded surface at the top of the Cretaceous Porto de Mós Formation, at the base of the overlying LPF succession, is a wave-cut platform representing the Miocene transgressive surface.
Carlos Marques da Silva; Mário Cachão; Ana Cristina Rebelo; Markes E. Johnson; B. Gudveig Baarli; Ana Santos; Eduardo J. Mayoral. Paleoenvironment and taphonomy of lower Miocene bivalve and macroid assemblages: the Lagos Biocalcarenite (Lagos-Portimão Formation, southern Portugal). Facies 2019, 65, 6 .
AMA StyleCarlos Marques da Silva, Mário Cachão, Ana Cristina Rebelo, Markes E. Johnson, B. Gudveig Baarli, Ana Santos, Eduardo J. Mayoral. Paleoenvironment and taphonomy of lower Miocene bivalve and macroid assemblages: the Lagos Biocalcarenite (Lagos-Portimão Formation, southern Portugal). Facies. 2019; 65 (2):6.
Chicago/Turabian StyleCarlos Marques da Silva; Mário Cachão; Ana Cristina Rebelo; Markes E. Johnson; B. Gudveig Baarli; Ana Santos; Eduardo J. Mayoral. 2019. "Paleoenvironment and taphonomy of lower Miocene bivalve and macroid assemblages: the Lagos Biocalcarenite (Lagos-Portimão Formation, southern Portugal)." Facies 65, no. 2: 6.
Markes E. Johnson. Rhodoliths. Encyclopedia of Solid Earth Geophysics 2019, 1426 -1436.
AMA StyleMarkes E. Johnson. Rhodoliths. Encyclopedia of Solid Earth Geophysics. 2019; ():1426-1436.
Chicago/Turabian StyleMarkes E. Johnson. 2019. "Rhodoliths." Encyclopedia of Solid Earth Geophysics , no. : 1426-1436.
A synthetic model is presented to enlarge the evolutionary framework of the General Dynamic Model (GDM) and the Glacial Sensitive Model (GSM) of oceanic island biogeography from the terrestrial to the marine realm. The proposed ‘Sea‐Level Sensitive’ dynamic model (SLS) of marine island biogeography integrates historical and ecological biogeography with patterns of glacio‐eustasy, merging concepts from areas as diverse as taxonomy, biogeography, marine biology, volcanology, sedimentology, stratigraphy, palaeontology, geochronology and geomorphology. Fundamental to the SLS model is the dynamic variation of the littoral area of volcanic oceanic islands (defined as the area between the intertidal and the 50‐m isobath) in response to sea‐level oscillations driven by glacial–interglacial cycles. The following questions are considered by means of this revision: (i) what was the impact of (global) glacio‐eustatic sea‐level oscillations, particularly those of the Pleistocene glacial–interglacial episodes, on the littoral marine fauna and flora of volcanic oceanic islands? (ii) What are the main factors that explain the present littoral marine biodiversity on volcanic oceanic islands? (iii) How can differences in historical and ecological biogeography be reconciled, from a marine point of view? These questions are addressed by compiling the bathymetry of 11 Atlantic archipelagos/islands to obtain quantitative data regarding changes in the littoral area based on Pleistocene sea‐level oscillations, from 150 thousand years ago (ka) to the present. Within the framework of a model sensitive to changing sea levels, we discuss the principal factors affecting the geographical range of marine species; the relationships between modes of larval development, dispersal strategies and geographical range; the relationships between times of speciation, modes of larval development, ecological zonation and geographical range; the influence of sea‐surface temperatures and latitude on littoral marine species diversity; the effect of eustatic sea‐level changes and their impact on the littoral marine biota; island marine species–area relationships; and finally, the physical effects of island ontogeny and its associated submarine topography and marine substrate on littoral biota. Based on the SLS dynamic model, we offer a number of predictions for tropical, subtropical and temperate volcanic oceanic islands on how rates of immigration, colonization, in‐situ speciation, local disappearance, and extinction interact and affect the marine biodiversity around islands during glacials and interglacials, thus allowing future testing of the theory.
Sérgio P. Ávila; Carlos Melo; Björn Berning; Nuno César de Sá; Rui Quartau; Kenneth F. Rijsdijk; Ricardo Ramalho; Ricardo Cordeiro; Adriano Pimentel; Lara Baptista; António Medeiros; Artur Gil; Markes E. Johnson. Towards a ‘Sea‐Level Sensitive’ dynamic model: impact of island ontogeny and glacio‐eustasy on global patterns of marine island biogeography. Biological Reviews 2018, 94, 1116 -1142.
AMA StyleSérgio P. Ávila, Carlos Melo, Björn Berning, Nuno César de Sá, Rui Quartau, Kenneth F. Rijsdijk, Ricardo Ramalho, Ricardo Cordeiro, Adriano Pimentel, Lara Baptista, António Medeiros, Artur Gil, Markes E. Johnson. Towards a ‘Sea‐Level Sensitive’ dynamic model: impact of island ontogeny and glacio‐eustasy on global patterns of marine island biogeography. Biological Reviews. 2018; 94 (3):1116-1142.
Chicago/Turabian StyleSérgio P. Ávila; Carlos Melo; Björn Berning; Nuno César de Sá; Rui Quartau; Kenneth F. Rijsdijk; Ricardo Ramalho; Ricardo Cordeiro; Adriano Pimentel; Lara Baptista; António Medeiros; Artur Gil; Markes E. Johnson. 2018. "Towards a ‘Sea‐Level Sensitive’ dynamic model: impact of island ontogeny and glacio‐eustasy on global patterns of marine island biogeography." Biological Reviews 94, no. 3: 1116-1142.
The increasing interest in geotourism has prompted the need for quantitative assessments of geosites as a fundamental step in the application of geoconservation strategies, in order to assure sustainable planning, management and use of natural resources. The improvement of methodologies used to evaluate geosites dictates the revision of previous assessments on a regular basis. Santa Maria Island in the Azores Archipelago is renowned for its palaeontological heritage. Herein, we present the results of a re-evaluation of 17 fossiliferous geosites, based on an updated methodology in which four main independent criteria are considered: (1) scientific value; (2) educational value; (3) touristic value; and (4) degradation risk. These new results were compared with a previous evaluation of the same geosites, based on the Q-value. Our results show that an evaluation of the fossiliferous geosites based on independent criteria is more suitable, especially for political and economic stakeholders. The study of these geosites also permitted the development of high-quality promotional products for the Regional Government of the Azores, as in the case of the “House of the Fossils” museum, the “Fossils Route” and the newly formed “Santa Maria PalaeoPark,” making this island a good example of a successful joint venture between science, political decision-makers, geoconservation management strategies, sustainable tourism and education.
Vera B. Raposo; Carlos S. Melo; Luís Silva; Anunciação Ventura; Rita Câmara; Joana Pombo; Markes E. Johnson; Sérgio P. Ávila. Comparing Methods of Evaluation of Geosites: The Fossiliferous Outcrops of Santa Maria Island (Azores, NE Atlantic) as a Case Study for Sustainable Island Tourism. Sustainability 2018, 10, 3596 .
AMA StyleVera B. Raposo, Carlos S. Melo, Luís Silva, Anunciação Ventura, Rita Câmara, Joana Pombo, Markes E. Johnson, Sérgio P. Ávila. Comparing Methods of Evaluation of Geosites: The Fossiliferous Outcrops of Santa Maria Island (Azores, NE Atlantic) as a Case Study for Sustainable Island Tourism. Sustainability. 2018; 10 (10):3596.
Chicago/Turabian StyleVera B. Raposo; Carlos S. Melo; Luís Silva; Anunciação Ventura; Rita Câmara; Joana Pombo; Markes E. Johnson; Sérgio P. Ávila. 2018. "Comparing Methods of Evaluation of Geosites: The Fossiliferous Outcrops of Santa Maria Island (Azores, NE Atlantic) as a Case Study for Sustainable Island Tourism." Sustainability 10, no. 10: 3596.
A seabed sediment-sampling survey conducted on the Pico insular shelf found abundant rhodoliths between −64 and −73 m off the south coast of the island. These were small and mainly ellipsoidal in shape with a maximum diameter of 3.75 cm. Granules and small pebbles of eroded basalt were also a typical component of these samples. Thin algal crusts were secreted on basalt pebbles by the coralline red algae Phymatolithon calcareum which, in turn, were covered by Lithophyllum incrustans. Additional samples were collected by snorkelling at Maré (Lajes do Pico), a shallow lagoon (2–4 m in depth) on the south coast. Here, rhodoliths are mostly spheroidal and bigger (maximum diameter of 4.75 cm), formed by thin thalli of P. calcareum. Based on these results (distribution of shapes and species) and previous work on the characteristics of fossil specimens from Neogene deposits on Santa Maria Island (Azores) and other North Atlantic Archipelagos, an empirical depositional model is proposed for the development of rhodoliths on the Pico Island shelf: (1) Nearshore rhodoliths, formed solely by P. calcareum, are subjected to a wide range of currents and waves resulting in their spheroidal shapes. However, those of Maré lagoon are protected from offshore transport and tend to grow larger than deep-water rhodoliths; (2) Although not sampled, there must be middle shelf rhodoliths formed solely by P. calcareum that tend to form more ellipsoidal shapes due to seafloor oscillatory movements caused by waves crossing the shelf; (3) During storms, these middle shelf rhodoliths are then transported to the outer shelf, where L. incrustans overgrows the initial cover of P. calcareum; Shallow associations are normally bigger, reflecting therefore, a longer life span than the deeper associations. Transport by storms appears to be an important factor in the formation of some deep-water rhodoliths around volcanic oceanic islands subjected to high-wave energy. However, their exposure to an energetic environment and likely frequent offshore transport does not allow them to grow as big as those from shallow-water.
Ana Cristina Rebelo; Markes E. Johnson; Rui Quartau; Michael W. Rasser; Carlos S. Melo; Ana Neto; Fernando Tempera; Patrícia Madeira; Sérgio P. Ávila. Modern rhodoliths from the insular shelf of Pico in the Azores (Northeast Atlantic Ocean). Estuarine, Coastal and Shelf Science 2018, 210, 7 -17.
AMA StyleAna Cristina Rebelo, Markes E. Johnson, Rui Quartau, Michael W. Rasser, Carlos S. Melo, Ana Neto, Fernando Tempera, Patrícia Madeira, Sérgio P. Ávila. Modern rhodoliths from the insular shelf of Pico in the Azores (Northeast Atlantic Ocean). Estuarine, Coastal and Shelf Science. 2018; 210 ():7-17.
Chicago/Turabian StyleAna Cristina Rebelo; Markes E. Johnson; Rui Quartau; Michael W. Rasser; Carlos S. Melo; Ana Neto; Fernando Tempera; Patrícia Madeira; Sérgio P. Ávila. 2018. "Modern rhodoliths from the insular shelf of Pico in the Azores (Northeast Atlantic Ocean)." Estuarine, Coastal and Shelf Science 210, no. : 7-17.