Cover Page

Vol 51, No 2 (2024)

Column-like geoforms and caves (<2 m high) in Grutas del Palacio (SW Uruguay). Columnar structures are a distinctive feature of the uppermost part of the Upper Cretaceous continental deposits (Asencio Formation) in SW Uruguay. They represent the casts of rotting tree trunks that were then filled with reworked iron-rich materials, and covered by iron-rich siliceous sandstones. These structures are evidence of the existence in this sector of an old flooded forest Upper Cretaceous in age, with large trees and developed in a warm, seasonally humid climate. Photography by Ferran Colombo.
Cover Page

Vol 51, No 1 (2024)

Canvas painting by Diógenes A. Gómez showing Galeras volcano (Nariño, Colombia) in activity (background) and a fragment of the dihedral rock where the El Higuerón pictograph was made (foreground, white rectangle). On the left side of the rock, the motif representing the volcano is the arched black feature with zigzag or wavy yellow and red lines on top. Both the volcanic motif, as well as the anthropomorphic figure beneath it, have been enclosed in a white circle for clarity. A similar anthropomorphic figure appears in the forehead of the indigenous character that is painting the pictograph. Photograph taken by John J. Sánchez, the artwork is from his private collection in Medellín (Colombia).


Cover Page

Vol 50, No 3 (2023)

Pyroclastic density currents decoupled from a vertical eruptive column during the first pulse (22 April 2015) of the Calbuco eruption as seen from the northwest. Tephrostratigraphy revealed these flows mostly affected the Tepu river, and travelled at a velocity of 35 m/s. Photo by Alfredo Becerra Parraguez - Puerto Varas Photography.
Cover Page

Vol 50, No 2 (2023)

Photograph showing a mature specimen with broken proximal end of Stimulograptus sedgwickii, collected in the middle Salto Macho Member of the La Chilca Formation, which crops out in the Poblete Norte Creek, Talacasto Range, Central Precordillera of San Juan. This graptolite is the index taxon of its homonymous Biozone from the upper Aeronian (Silurian). The scale bar equals 1 mm (Photography by Fernando E. Lopez).
Cover Page

Vol 50, No 1 (2023)

Photograph taken by Dr. Joseph Martinod of a glacially polished rock outcrop on the southern shore of Lago Bayo, on the road between Puerto Tranquilo and Ventisquero Exploradores in the Aysen Region. The 10Be exposure age is 14.05±0.94 ka, interpreted as the minimum age of glacial retreat in the Bayo River
Valley (Aguilar et al., 2023).


Cover Page

Vol 49, No 3 (2022)

Early-middle Miocene fossil bearing fluvial sandstone of the Cerro Boleadoras Formation in the Cerro Boleadoras area, western slope of the Meseta del Lago Buenos Aires, northwestern Santa Cruz Province, Argentina (Photography M. Susana Bargo).
Cover Page

Vol 49, No 2 (2022)

Oblique aerial view of modern delta at Río Dunas and perched delta terrace that formed as a result of punctuated regression at Patagonian Lake General Carrera. (Photography by Brian Hynek, Nov. 2018).
Cover Page

Vol 49, No 1 (2022)

Summit of Maipo volcano (5,300 m), Caldera del Diamante, Central Andes (34°09’50’’ S; 69°49’53’’ W). Glaciers and snowfields on the crater of Maipo volcano, in the background the Laguna del Diamante lake (Argentina) (Nov. 2021). Rising temperatures and reduced snowfall are degrading the glacial environment. Ancient glaciers could be today remnants of glaciers and snowfields (Photography by Andrés Lo Vecchio).


Cover Page

Vol 48, No 3 (2021)

After months of the beginning of the elusive Mondaca Volcano eruption, a prominent succession of at least 20 m thick tephra fall deposit accumulated to the south and southeast of its emission center. In this aerial view taken towards the NNE the detail of the tephra fall sequence is exhibited, whose collapse contributed recharging solid materials of the December 3, 1762 lahar along the Lontué and Mataquito rivers (Photography by José Antonio Naranjo).
Cover Page

Vol 48, No 2 (2021)

Aeolian, fine-grained red sandstone of the Cisuralian Patquia Formation displaying cross-bedding (San Juan, Argentina). The scale geo/paleo pick is about 60 cm long (Photography by Bárbara Cariglino).
Cover Page

Vol 48, No 1 (2021)

Quartz, barite, massive silica and kaolinite breccia with vuggy silica clasts and native gold. Ledge Dumbo, El Guanaco mine, Antofagasta region, Chile. The scale bar represents 0.5 cm (Photography by Sebastián Jovic).


Cover Page

Vol 47, No 3 (2020)

Pisolites or caverns pearls nest formed on the ground of one of the underground filtration galleries, locally called socavones, of the Pica Oasis (Region of Tarapacá, Chile). The pisolites are composed of calcium carbonate which covers the walls of some socavones excavated in the Pleistocene-Holocene alluvial deposits. The pisolites nest is approximately 8 cm in diameter (Photography by Carlos Abellanosa).
Cover Page

Vol 47, No 2 (2020)

Block diagram illustrating the two-stage paleogeographic evolution of the Andean Margin at 29°S, northern Chile, during the Triassic. Both stages, Early to Middle Triassic and Late Triassic, involve the development of intra-arc and fore-arc basins. Note the westward shift of the intra-arc basin and the progradation of the fore-arc basin between the two stages. Thick black arrows represent sediment input from identified source areas to the fore-arc basins (Figure drawn by Esteban Salazar).
Cover Page

Vol 47, No 1 (2020)

Lajas Formation lower to middle section (Middle Jurassic) at Bajada de Los Molles area, Neuquén basin, Argentina. Redrawn stratigraphic column showing transition between offshore, prodelta and delta front deposits. Offshore deposits show massive arrangements due to intense bioturbation, whereas heterolithic prodelta deposits preserve primary sedimentary structures. (Photography by Nerina Canale. Redraw by Juan José Ponce).


Cover Page

Vol 46, No 3 (2019)

Ovule/seed compression referred to the genus Cordaicarpus Geinitz, 1862 emend. Archangelsky, 2000. 0.6 cm in width. The specimen comes from the Agua de la Zorra Formation (Upper Triassic) Mendoza Province, Argentina. The photograph was taken with a LEICA M60 binocular stereoscopic microscope with a LEICA DMC2900 integrated camera. (Photography by Tomás E. Pedernera).
Cover Page

Vol 46, No 2 (2019)

Exposure of the lower to middle part of the Santa Cruz Formation showing thick floodplain fluvial deposits, composed of intercalated mudstone and thin sandstone beds. Sandstone beds show sharp bases, sometimes erosive, and commonly wedge shape. Few thick, lenticular fluvial channel deposits also intercalate. In the background, the Río Tarde (whitish), the Posadas Basalt (dark grey) and the El Chacay (greenish) formations are observed (Photography by José I. Cuitiño).
Cover Page

Vol 46, No 1 (2019)

Stromatolitic formations in a lagoon situated in the south-east of the Agua Amarga Salar (Atacama Region, Chile). The part outside the water is covered by halite (white crust), while the part inside the water it is formed by gypsum and dust dragged by the wind and precipitated in the lagoon (Photography by Oscar Ercilla).


Cover Page

Vol 45, No 3 (2018)

Glacial cirques located to the west of Sierra Baguales mountain range, southern Patagonia. These represent alpine glaciations isolated from the Pleistocene Ice Sheet located to the west. The evolution of these alpine glaciers was controlled mainly by cirques elevation and aspect, under cold and dry local conditions (Image Google Earth © modified by Michael Kaplan).
Cover Page

Vol 45, No 2 (2018)

View of Maradona Fault System in the eastern piedmont of Central Precordillera, San Juan, Argentina. Neogene rocks overlie Late Pleistocene fanglomerates (Photo by Gabriela Lara).
Cover Page

Vol 45, No 1 (2018)

Front fluctuations of Upsala glacier since 1914 to 2016, Upsala Channel, Argentino Lake, Santa Cruz, Argentina. (Landsat image, false color composition, created by S. Moragues).


Cover Page

Vol 44, No 3 (2017)

"Crystal and vitric tuffs with pumiceous fragments and reverse grading. Lomas del Campanario Unit (Middle to Upper Miocene), eastern slope of Frontal Cordillera, San Juan province, Argentina (Photography by Vanesa D. Litvak)."
Cover Page

Vol 44, No 2 (2017)

"Fossil stromatolite from Navidad Paleoseep located in the emerged coast of Central Chile (33°56' S). Section represents microbialites of chemosynthetic origin associated to methane seepage from the seabed (Photography by Emilio Mena-Hodges)."
Cover Page

Vol 44, No 1 (2017)

“Outcrop at Punta Quiaca, southern end of Isla Llancahue. Metasandstones are boudinaged within micaschists. The main vertical foliation trending N35°W is a crenulation foliation; isoclinal folds of a previous foliation are locally observed in the microlithons. A metasandstone layer similar to the ones shown in the photograph, yielded a maximum depositional age of 52.5±0.5 Ma from the analyses of detrital zircon grains. Diameter of coin is ca 2 cm. (Photograph by C. Mark Fanning).”


Cover Page

Vol 43, No 3 (2016)

"Deviatoric stress inside an oceanic slab after few million years of subduction as simulated by a numerical model assuming a temperature-dependent elasto-visco-plastic rheology. Red regions indicate high flexural stresses mostly at the base of the bended slab (model and figure created by M. Gerbault)."
Cover Page

Vol 43, No 2 (2016)

"Crevasse channels in cross-bedded medium-to coarse-grained sandstone, with conglomerate lags and bearing some vertebrate fossils from the Río Seco de la Quebrada Formation in Quebrada del Durazno, Mendoza, Argentina (Photography by Adriana Mancuso)."
Cover Page

Vol 43, No 1 (2016)

"Panoramic view of the active crater of Planchón-Peteroa volcano. The photo was taken in November 2010, two months after the onset of the eruption. Note the absence of an acid lake and the intense fumarolic activity. View from the W (photo by Daniel Tormey)."


Cover Page

Vol 42, No 3 (2015)

"Agate sample from the Cerro Negro Formation in Cordón de Lila (Permian), Chile. The agates are present in volcanic rocks (rhyodacites/dacites), which undergone late- to post-volcanic hydrothermal alteration (Photography by Jens Götze)."
Cover Page

Vol 42, No 2 (2015)

“Glaciolacustrine sediments cropping-out at "El Canal" stratigraphic trench, which cuts the late-glacial moraine belts nearby Torres del Paine National Park (Chile). The image exposes a mixture of glaciolacustrine sediments including ice rafted debris interlayered with gravels deposited from gentle lake-bottom currents within a high-sedimentary rate subaqueous environment. The cobble in the upper part is a dropstone (Photo by Juan-Luis García).”
Cover Page

Vol 42, No 1 (2015)

"Medium to coarse sandstone and fine conglomerate deposits with trough and high angle cross stratification and multiple internal reactivaction surfaces assigned to hyperpycnal channel facies in fluvial dominated deltaic systems. Arroyo Covunco, Neuquén, Argentina (Photography from Juan José Ponce)."


Cover Page

Vol 41, No 3 (2014)

"General view of the outcrops of one of the most important Early Miocene (Castillo Formation) vertebrate assemblages, Pansantacrucian South American Land Mammal Age in Cerro La Cruz locality, Sierra de La Baragua, Lara state, Venezuela. (Photo by Ascanio Rincón)."
Cover Page

Vol 41, No 2 (2014)

"Outcrop of the strike-slip Hope fault at Hope Hill, east of Lago Fagnano, Chile (Photography taken by M. Menichetti)."
Cover Page

Vol 41, No 1 (2014)

"Cerro Mesón Alto Massif and possible landslide source area of the chaotic deposit south of the Yeso Dam at 33°40'S, Yeso Valley, central Chile. (Photography from S. Sepúlveda)".


Cover Page

Vol 40, No 3 (2013)

"Fragmented maxillary with well-preserved dental series of a notohipid ungulate allied to Notohippus toxodontoides Ameghino, 1891, collected from the fluvial succession of the Santa Cruz Formation (Early Miocene, Burdigalian age) in Sierra Baguales, Última Esperanza Province, Chile. (Photography from J. L. Oyarzún)".

Cover Page

Vol 40, No 2 (2013)

"View of Chaitén lava dome looking north on 26 May 2008. At this time, the eruption was undergoing simultaneous explosion and effusion of new lava (on left-central side of dome). See Pallister et al. (this volume) for details. (Photography from J. Marso, United States Geological Survey)"
Cover Page

Vol 40, No 1 (2013)

"Sail Rock is a small volcano located some 35 km southwest of Deception Island. It rises about 30 m above sea level and features a sail-like shape (hence its name). The stack marks the top of a volcano, the rest of which is submerged below sea level. The age of Sail Rock is unknown, and the stack is composed of layers of pyroclastic breccia and tuffs alternating with lava flows. It was not discovered before March 1987 and, as of today, has been visited only twice. (Photography from S. Kraus)"


Cover Page

Vol 39, No 3 (2012)

"Vista general de las vulcanitas y piroclastitas del Miembro Puesto Tillerías (Burdigaliano, Mioceno Inferior), Formación Sierra Negra; atravesadas por diques básicos de la Formación Desfiladero Negro (Tortoniano, Mioceno Superior). Cara suroriental de la sierra de Huantraico, provincia del Neuquén, República Argentina. (Fotografía de A. Garrido)"
Cover Page

Vol 39, No 2 (2012)

"Southward view of the east-vergent Vega de los Patos anticline, cored by the Huitrín Formation evaporites and flanked by the Diamante Formation red beds, developed in a region of thin-skinned deformation of the Malargüe fold-and-thrust belt, Mendoza Province, Argentina (34°39'30''S-69°41'20''W)(Photography by M. Turienzo)".