Alejandro Cearreta

Alejandro Cearreta
Universidad del País Vasco / Euskal Herriko Unibertsitatea | UPV/EHU · Geology

Professor of Micropalaeontology
Head of the Geology Department

About

229
Publications
123,951
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Introduction
Alejandro Cearreta currently works at the Geology Department, Universidad del País Vasco UPV/EHU, Spain. Alejandro does research in Quaternary Micropalaeontology and Geology. He studies natural evolution and human transformation of coastal environments during the Holocene and Anthropocene.
Additional affiliations
November 1988 - February 2022
Universidad del País Vasco / Euskal Herriko Unibertsitatea UPV/EHU
Position
  • Professor
Education
October 1983 - December 1986
University of Exeter
Field of study
  • Geology
September 1977 - September 1983
Universidad del País Vasco / Euskal Herriko Unibertsitatea UPV/EHU
Field of study
  • Geology

Publications

Publications (229)
Article
The Anthropocene defined as an epoch/series within the Geological Time Scale, and with an isochronous inception in the mid-20th century, would both utilize the rich array of stratigraphic signals associated with the Great Acceleration and align with Earth System science analysis from where the term Anthropocene originated. It would be stratigraphic...
Article
Full-text available
Se ha analizado el registro sedimentario reciente del estuario del Nalón a partir de dos sondeos intermareales que han sido datados mediante 210Pb y 137Cs. Los resultados muestran por primera vez sus asociaciones características de foraminíferos bentónicos, constituidas por un total de 46 especies, así como los importantes cambios experimentados po...
Chapter
Full-text available
The Anthropocene Working Group is preparing the case for the definition of a new stratigraphic Epoch: this requires the demonstration of an objective change in properties of a geological archive over time. As each property being examined for this distinction can be considered as a time series, we encounter a classic scientific problem of distinguis...
Chapter
Full-text available
Extinction, coupled with many other biological signals, is a major geological indicator of the Anthropocene. The introduction of non-native species, deforestation, depletion of fisheries and modification of coastal environments, domestication of animals, and the reconfiguration of terrestrial ecosystems are all evident in the geological record and...
Article
Full-text available
The most recent division of geological time is based on climate events caused by variations in the Earth’s orbit and axis of rotation on a scale of thousands of years. However, the magnitude of geological change caused by humankind through its still young technosphere, particularly since the mid-20th century, is negatively affecting the other class...
Article
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The Avilés estuary is one of the most important industrial ports in northern Spain, whose natural characteristics have been largely altered since the 1830s. Here, the environmental transformation of this estuary during the 19 th century is explored using a multi-proxy approach including benthic foraminiferal content, sedimentology (grain-size), tra...
Article
Full-text available
The Anthropocene was conceptualized in 2000 to reflect the extensive impact of human activities on our planet, and subsequent detailed analyses have revealed a sub- stantial Earth System response to these impacts begin- ning in the mid-20th century. Key to this understanding was the discovery of a sharp upturn in a multitude of global socio-economi...
Article
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La división del tiempo geológico más reciente está basada en eventos de carácter climático provocados por variaciones en la órbita y el eje de rotación de la Tierra a escala de miles de años. Sin embargo, la magnitud del cambio geológico causado por la humanidad a través de su joven tecnosfera está afectando negativamente a las otras esferas clásic...
Article
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Se analizaron la composición elemental de los sedimentos y la distribución y abundancia de microfósiles en dos zonas de marisma de la laguna costera Estero de Urías (Golfo de California, México) con el fin de determinar las características ambientales de este medio marino restringido. En los sedimentos se detectó un enriquecimiento por metales (en...
Article
Full-text available
A detailed study is presented of a 15.3‐m‐thick Pleistocene coastal terrace located on the Cantabrian coast (northern Spain). Stratigraphic, sedimentological, topographic and micropalaeontological information is combined with a chronology based on luminescence dating to characterize the deposits. The sedimentary succession records: (i) a basal tran...
Article
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In order to reconstruct the environmental evolution of the Deba and Urola estuaries located in the Basque Coast Geopark at millennial, centennial and decadal timescales, four long boreholes, three short cores and twelve surface samples were studied. Multiproxy analysis (foraminifera, trace metals and radioisotopes) shows the temporal transformation...
Article
Full-text available
We gathered total organic carbon (%) and relative abundances of benthic foraminifera in intertidal areas and transitional waters from the English Channel/European Atlantic Coast (587 samples) and the Mediterranean Sea (301 samples) regions from published and unpublished datasets. This database allowed to calculate total organic carbon optimum and t...
Article
Full-text available
The term Anthropocene initially emerged from the Earth System science community in the early 2000s, denoting a concept that the Holocene Epoch has terminated as a consequence of human activities. First associated with the onset of the Industrial Revolution, it was then more closely linked with the Great Acceleration in industrialization and globali...
Article
While we officially live in the Holocene epoch, global warming and many other impacts of global change have led to the proposal and wide adoption of the Anthropocene to define the present geological epoch. The Anthropocene Working Group (AWG) established that it should be treated as a formal stratigraphic unit, demonstrated by a reference level com...
Article
This work contributes to the ongoing work aiming at confirming benthic foraminifera as a biological quality element. In this study, benthic foraminifera from intertidal and transitional waters from the English Channel/ European Atlantic coast and the Mediterranean Sea were assigned to five ecological groups using the weighted-averaging optimum with...
Chapter
Stratigraphy provides insights into the evolution and dynamics of the Earth System over its long history. With recent developments in Earth System science, changes in Earth System dynamics can now be observed directly and projected into the near future. An integration of the two approaches provides powerful insights into the nature and significance...
Data
Supplementary material to Syvitski et al. 2020, see https://www.researchgate.net/publication/344685697_Extraordinary_human_energy_consumption_and_resultant_geological_impacts_beginning_around_1950_CE_initiated_the_proposed_Anthropocene_Epoch
Article
Full-text available
Growth in fundamental drivers—energy use, economic productivity and population—can provide quantitative indications of the proposed boundary between the Holocene Epoch and the Anthropocene. Human energy expenditure in the Anthropocene, ~22 zetajoules (ZJ), exceeds that across the prior 11,700 years of the Holocene (~14.6 ZJ), largely through combus...
Article
Full-text available
Bilboko itsasadarra Kantauri itsasoko estuariorik handiena izan zen garai batean. Azken 150 urteetan, kontrolik gabe isuri dira itsasadarrera meatzeetako, fabriketako eta etxeetako hondakinak. Horren ondorioz, ibaiaren ezaugarri fisiko-kimikoak narriatu egin ziren. Garapen jasanezin horren eraginez, 1970eko hamarkadarako itsasadarra estolda nabigag...
Article
In July 2019, the 15th National Quaternary Meeting was held in Bilbao, under the general theme of “Environmental Changes and Human Footprint”. This congress of the Spanish Quaternary Research Association (AEQUA) was organised locally by the Quaternary Formation and Research Unit of the UPV/EHU and had the support of different organisations, as the...
Article
This work deals with the microfaunal (benthic foraminifera) and geochemical (trace metals, ¹⁴C, ²¹⁰Pb, ¹³⁷Cs, and 239/240Pu) study of two boreholes (1200 and 1400 cm length) and three subtidal sediment cores (38–58 cm length) collected in the Pasaia estuary (northern Spain). Foraminiferal assemblages in the Holocene deposits depend on the paleogeog...
Article
Full-text available
La ría de Bilbao fue originalmente el estuario más grande del Cantábrico. Durante los últimos 150 años, la Ría ha recibido vertidos incontrolados de desechos mineros, industriales y domésticos que degradaron sus condiciones físico-químicas. Como consecuencia de este desarrollo insostenible, en la década de 1970 la Ría se había convertido en una clo...
Article
The historical anthropogenic impact on sediments from the Basque Mud Patch (southern Bay of Biscay) is explored using a multidisciplinary approach including the analysis of natural (²¹⁰Pb) and artificial (¹³⁷Cs, 239/240Pu) radiotracers, major elements (Al, Mn), metals (Zn, Pb, Cu, Cr), Pb isotopic ratios, and foraminiferal and pollen contents. The...
Article
Full-text available
This study describes a rapid method for sequential determination of uranium and plutonium isotopes in soil and sediment samples and its application to the study of Anthropocene sedimentary records. Different pretreatment methods have been tested (open-vessel digestion, borate salts fusion and NaOH salt fusion) achieving the complete dissolution of...
Article
Full-text available
Se han estudiado las asociaciones de foraminíferos de dos sondeos largos y uno corto en el estuario del Deba con el fin de realizar la interpretación ambiental de su registro sedimentario. Adicionalmente, se han llevado a cabo análisis geoquímicos en el sondeo corto, y análisis microfaunísticos y geoquímicos en ocho muestras superficiales tomadas a...
Article
Full-text available
The transformation of two intertidal environments from northern Spain during the last 150 years shows an evolution from a tidal flat into a salt marsh environment, with an intermediate transitional stage. The environment of deposition was reconstructed based on benthic foraminifera and sand content. Sediments were put into a temporal framework usin...
Article
Full-text available
El País Vasco presenta una larga tradición cuaternarista, dentro de la cual podemos destacar la publicación en el año 1917 de los primeros trabajos científicos sobre Prehistoria vasca por José Miguel de Barandiaran, Telesforo de Aranzadi y Enrique Eguren, la fundación en 1947 de la Sociedad de Ciencias Aranzadi para la investigación del medio natur...
Article
Full-text available
Debido a los compromisos políticos vacíos de contenido o que no han sido respetados por los gobiernos, las emisiones de gases de efecto invernadero siguen en aumento a pesar de las advertencias de la comunidad científica.
Article
The Bilbao estuary is one of the most polluted areas on the northern coast of Spain, owing to the direct disposal of urban effluents and wastewaters from mining and industrial activities that has occurred during the last 170 years. Recent sediment records collected from the inner Abra of Bilbao bay were examined using a multidisciplinary approach i...
Conference Paper
Full-text available
Holocene environmental evolution of the Oka Estuary (Urdaibai Biosphere Reserve, southeastern Bay of Biscay): response to postglacial sea-level rise): Fluvial paleovalleys provide critical data to study the temporal superposition of depositional environments during the Holocene postglacial sea-level rise. We study eight boreholes that reached bedro...
Book
Full-text available
Entre los días 1-5 de julio 2019 se ha celebrado en Bilbao la XV Reunión Nacional de Cuaternario. Este congreso de la Asociación Española para el Estudio del Cuaternario (AEQUA) ha sido organizado localmente por la Unidad de Formación e Investigación en Cuaternario de la UPV/EHU y, entre sus distintas actividades, ha incluido 2 salidas de campo. Un...
Book
Full-text available
El País Vasco presenta una larga tradición cuaternarista, dentro de cuyos principales hitos se encuentra la publicación en el año 1917 de los primeros trabajos científicos sobre prehistoria vasca realizados por José Miguel de Barandiaran, Telesforo de Aranzadi y Enrique Eguren, la fundación en 1947 de la Sociedad de Ciencias Aranzadi para la invest...
Chapter
Full-text available
Uno de los primeros trabajos cuaternaristas sobre la costa vasca fue publicado por el geólogo francés M. E. Jacquot (1864) quien exploró cuidadosamente los 15 km de acantilados que se extienden entre San Juan de Luz y Biarritz. En ese trabajo, Jacquot señaló en Bidart y Biarritz un depósito arenoso con gravas y lechos de arcillas que contenían lign...
Book
Full-text available
Entre los días 1-5 de julio 2019 se ha celebrado en Bilbao la XV Reunión Nacional de Cuaternario. Este congreso de la Asociación Española para el Estudio del Cuaternario (AEQUA) ha sido organizado localmente por la Unidad de Formación e Investigación en Cuaternario de la UPV/EHU. El País Vasco presenta una larga tradición cuaternarista, dentro de c...
Chapter
Full-text available
Rock magnetic properties of 13 samples of surficial materials and 160 samples of recent sediments obtained from 7 sedimentary cores along the Bilbao estuary have been analyzed in order to investigate the magnetic fingerprint of anthropogenic pollution in this area. The results have been correlated to previously published heavy metal concentrations,...
Chapter
Full-text available
In order to reconstruct the possible recent anthropogenic impact recorded in the Basque mud patch, 3 cores obtained at around 100 m depth in front of the Guipuzcoan coast during the French oceanographic campaign Euskased (Euska2) have been studied. Their multiproxy analysis (metals, foraminifera, pollen, carbonaceous particles and short-lived radio...
Chapter
Full-text available
In order to reconstruct the environmental evolution of the estuaries in the Basque Coast Geopark at different temporal scales (millennial, centennial, decadal), different long and short cores and surface samples were retrieved and studied. Their multiproxy analysis (metals, foraminifera, pollen and radioisotopes) shows their temporal transformation...
Chapter
Full-text available
El Antropoceno geológico se diferencia en cierta medida de otras interpretaciones del Antropoceno que han ido apareciendo en los últimos años, ya que las ciencias sociales, las humanidades y las artes se han interesado por este concepto y lo han analizado a través de las herramientas conceptuales de sus propias disciplinas. Parece claro que aceptar...
Book
Full-text available
El Grupo de Etnografía del Museo Plasentia de Butrón se constituyó en el año 2016 con objeto de estudiar e interpretar diferentes aspectos del patrimonio cultural y ambiental de Uribe Kosta. Los miembros del grupo se conocieron asistiendo y colaborando en las Jornadas de Historia de Plentzia-Uribe Kosta y decidieron asociarse en el seno del Museo p...
Chapter
Full-text available
La marisma de Txipio se encuentra frente al casco urbano de Plentzia en la margen izquierda de la Ría del Butroe. Fue ocupada con fines agrícolas desde mediados del siglo XIX y abandonada un siglo después. Durante ese periodo se utilizó como zona de cultivo mediante su relleno artificial y la construcción de canales de drenaje para los aportes de a...
Article
Full-text available
El Antropoceno sería una unidad de la historia de la Tierra que podría formar parte de la Escala del Tiempo Geológico. Si bien los cambios asociados con el Antropoceno han sido hasta ahora geológicamente breves, sus consecuencias han provocado una modificación muy evidente del planeta hacia una nueva trayectoria, con efectos que persistirán durante...
Article
We analyse the ‘three flaws’ to potentially defining a formal Anthropocene geological time unit as advanced by Ruddiman (2018). (1) We recognize a long record of pre-industrial human impacts, but note that these increased in relative magnitude slowly and were strongly time-transgressive by comparison with the extraordinarily rapid, novel and near-g...
Article
Full-text available
El alcance social y académico del Antropoceno ha crecido de una manera sorprendente. Este concepto se acuñó para materializar nuestra percepción de que las actividades humanas han cambiado el Sistema Tierra. El comportamiento de los océanos, la atmósfera, la superficie terrestre, la criosfera, la biosfera y el clima ya no es el mismo que ha caracte...
Book
Full-text available
The Anthropocene, a term launched into public debate by Nobel Prize winner Paul Crutzen, has been used informally to describe the time period during which human actions have had a drastic effect on the Earth and its ecosystems. This book presents evidence for defining the Anthropocene as a geological epoch, written by the high-profile international...
Chapter
Sea-level change is one of the most important consequences of Quaternary climate variability. The association of human population centres with lowland coastal regions dates back to early civilisations, when people congregated at river mouths, deltas and estuaries because of abundant and accessible food sources. The emergence and rapid expansion of...
Chapter
The Basque estuaries represent drowned river valleys that were firstly flooded by the sea due to a climate-change-induced sea-level rise 8500 yr ago, and subsequently, infilled with a general shallowing sequence. Basque estuaries developed from an initial fluvial environment followed by a firstly marine and secondly brackish depositional system.
Chapter
The first data available on the interaction between human beings and the Basque estuaries are situated in the Prehistory, after the last glacial maximum.
Chapter
El registro sedimentario depositado durante los últimos siglos en las marismas de la Ría de Plentzia permite reconstruir los procesos más importantes que han operado ahí a través del tiempo y que responden tanto a factores locales (ocupación humana de estas marismas con fines agrícolas) como de carácter global (variaciones en el nivel marino como c...
Article
Full-text available
The recent sedimentary record of the Pasaia bay has been analysed using 3 subtidal cores. These contain fine-grained sediments, very high metallic pollutants and very scarce microfauna. They are indicative of negative environmental conditions that have been persistent in this area at least during the last 6 decades. These characteristics are decisi...
Chapter
Foraminifera are abundant in all marine and coastal settings. Their microfossils have proved to be particularly useful in Quaternary stratigraphic, paleoenvironmental, and paleoclimate reconstructions. Since the 1980s, benthic foraminifera have been employed to answer important archaeological questions mainly focused on the study of provenance and...
Article
Full-text available
¿Existe el Antropoceno? Los expertos debaten si la huella que estamos dejando en los sedimentos de la Tierra reúne las condiciones para definir una nueva época geológica.
Article
This work tackles a multidisciplinary study on the recent sedimentary record of the Bilbao estuary (northern Spain), which is the backbone of a city that was primarily industrial and now is widely recognized as a successful example of urban transformation. Although hotspots of heavily polluted materials still remain at the mouth of the two main tri...
Article
High-quality relative sea-level (RSL) data reveal spatial and temporal variations in crustal movements during the Holocene, which are used for many applications, ranging from calibrating models of earth rheology and ice sheet reconstructions to the development of coastal lowlands and human occupation. Here, we present a Holocene RSL database for th...
Article
Full-text available
Plásticos, metales pesados, hidrocarburos, cemento..., la ciencia investiga las señales que indican el inicio del Antropoceno
Article
The Anthropocene as a potential new unit of the International Chronostratigraphic Chart (which serves as the basis of the Geological Time Scale) is assessed in terms of the stratigraphic markers and approximate boundary levels available to define the base of the unit. The task of assessing and selecting potential Global Boundary Stratotype Section...
Conference Paper
Full-text available
The Anthropocene, as a potential new unit of the International Chronostratigraphic Chart, is assessed in terms of stratigraphic markers and approximate boundary levels available to define the unit base. The task of assessing and selecting potential GSSP candidate sections, a requirement in seeking formalisation of the term, is being actively pursue...
Article
Full-text available
Abstract This work presents a synthesis on the stratigraphy and geochronology of the Quaternary Period after the chronological updating ratified by the International Commission on Stratigraphy (ICS-IUGS) and the International Union for Quaternary Research (INQUA). We show the more recent (updated) stratigraphic, chronologic and paleoclimatic data...
Chapter
Full-text available
Tras la II Guerra Mundial, en 1945 se crea Naciones Unidas para salvar a las generaciones futuras de la devastación de conflictos internacionales y en 1948 se adopta la Declaración Universal de los Derechos Humanos. Paralelamente, estos últimos 70 años han visto la transformación más rápida de la relación entre los seres humanos y el medio natural,...
Chapter
Salt marshes reduce wave energy and offer natural protection from storms and floods. In the last centuries these coastal areas have been intensely impacted by human activities worldwide. In northern Spain, more than 50% of the original salt marshes have been reclaimed with agricultural purposes since the 17th century. However, many of these coastal...
Article
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Article
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The recent sedimentary record in the subtidal area of the inner Abra of Bilbao has been studied using 2 cores of 64 and 56 cm in length. General accumulation of materials shows mainly a muddy character with a moderate abundance of benthic foraminifera and a decrease in metal concentrations through time as a consequence of the local industrial histo...
Data
This is the link to the press release from University of Leicester for the new AWG paper authored by the above members of the working group: https://www2.le.ac.uk/offices/press/press-releases/2017/march/the-anthropocene-scientists-respond-to-criticisms-of-a-new-geological-epoch
Article
Full-text available
A range of published arguments against formalizing the Anthropocene as a geological time unit have variously suggested that it is a misleading term of non-stratigraphic origin and usage, is based on insignificant temporal and material stratigraphic content unlike that used to define older geological time units, is focused on observation of human hi...
Book
Full-text available
Level 4 of the cave of Pico Ramos (Muskiz, Bizkaia) is a shell midden occupied by the humans who visited the cave during the 6th and 5th millennium cal BC. This volumen includes the following studies: excavation, stratigraphy, chronology and materials; Holocene sea-level; vegetation, use of fuelwood and agriculture; identification and exploitation...
Article
Full-text available
We assess the scale and extent of the physical technosphere, defined here as the summed material output of the contemporary human enterprise. It includes active urban, agricultural and marine components, used to sustain energy and material flow for current human life, and a growing residue layer, currently only in small part recycled back into the...
Article
Full-text available
Stratigraphy provides insights into the evolution and dynamics of the Earth System over its long history. With recent developments in Earth System science, changes in Earth System dynamics can now be observed directly and projected into the near future. An integration of the two approaches provides powerful insights into the nature and significance...
Article
Major Mediterranean deltas began to develop during a period between 8000 and 6000 yr BP when the rate of fluvial sediment input overtook the declining rate of sea-level rise. However, different authors have argued that the Ebro Delta primarily formed during the late Middle Ages as a consequence of increased anthropogenic pressure on its river basin...
Article
Sea-level rise (SLR) is one of the most conspicuous examples of the environmental impact of recent climate change. Since SLR rates are not uniform around the planet, local and regional data are needed for proper adaptation plans. 210Pb-dated sediment cores were analyzed to determine the trends of sediment accretion rates (SARs) at three tropical sa...