Pollen analysis was carried out on the infilling succession of the Fossa San Vito sinkhole, at the NE foothills of the Sarno Plain (Italy). Four 14C dates and six tephra layers constrain the pollen sequence between ca. 6000 and 500 cal yr BP. A forested environment, with a few signs of human activities, characterizes the pre-protohistoric period (ca. 6000–2750 yr BP). Stability of the arboreal pollen grains to non-arboreal pollen grains (AP/NAP) curve is due to climate-related opposite oscillations of deciduous and evergreen forest. In this period, the pyroclastic products from Neapolitan volcanoes that reached the upper Sarno Plain seem to have affected neither vegetation nor human activities. In the archaic and classic periods (ca. 2750–1500 yr BP), intensive deforestation and increase in anthropogenic indicators indicate the occurrence of grazing and crop activities managed by the main urban centers located in the plain: Pompeii, Stabiae, and Nuceria. After the Pompeii eruption in CE 79, a rapid re-afforestation and decline in all anthropogenic indicators testify to the temporary abandonment of the area, linked to the disastrous demise of the main economic centers. The upper plain was repopulated and exploited in the Late Ancient and Middle Ages (ca. 1700–500 yr BP), as indicated by the increase in all crop and grazing indicators.

A comprehensive morphostratigraphic and chronological study of the complete set of Holocene tephras from Tafí and Santa María valleys (northwestern Argentina), including analyses of compositional characteristics, is presented. Five ash tephras are recognized: V0 (El Rincón), V1a (Carreras 1a ash), V1b (Carreras 1b ash), V2a (Carreras 2 ash), and V2b (El Paso 3 ash). Two of them (V1b and V2b) are described for the first time in the study area. The new 14C and accelerator mass spectrometry ages presented, along with the previously published information, allows for the establishment of a chronological framework. The V0 tephra was deposited in the Early Holocene (about 10,000 yr BP), V1a and V1b were deposited in the Middle Holocene (about 4200 and 3500 yr BP, respectively), and V2a and V2b were deposited in the Late Holocene (after about 800 yr BP). The mineralogical, textural, and geochemical characterizations of the five tephras suggest that their tephra provenance was mainly from the back-arc region. However, the determination of the exact source of each tephra requires more accurate high-resolution tephrochronological studies. At least five major eruptions affected the Tafí and Santa María valleys in the last 10,000 yr.

Barton Peninsula is an ice-free area located in the southwest corner of King George Island (South Shetland Islands, Antarctica). Following the Last Glacial Maximum, several geomorphological features developed in newly exposed ice-free terrain and their distribution provide insights about past environmental evolution of the area. Three moraine systems are indicative of three main glacial phases within the long-term glacial retreat, which also favoured the development of numerous lakes. Five of these lakes were cored to understand in greater detail the pattern of deglaciation through the study of lacustrine records. Radiocarbon dates from basal lacustrine sediments enabled the reconstruction of the chronology of Holocene glacial retreat. Tephra layers present in lake sediments provided additional independent age constraints on environmental changes based on geochemical and geochronological correlation with Deception Island-derived tephra. Shrinking of the Collins Glacier exposed the southern coastal fringe of Barton Peninsula at 8 cal ky BP. After a period of relative stability during the mid-Holocene, the ice cap started retreating northwards after 3.7 cal ky BP, confining some glaciers within valleys as shown by moraine systems. Lake sediments confirm a period of relative glacial stability during the last 2.4 cal ky BP.

Only Ulleung and Baegdusan volcanoes have produced alkaline tephras in the Japan Sea/East Sea during the Quaternary. Little is known about their detailed tephrostratigraphy, except for the U–Oki and B–Tm tephras. Trace element analysis of bulk sediments can be used to identify alkaline cryptotephra because of the large compositional contrast. Five sediment cores spanning the interval between the rhyolitic AT (29.4 ka) and Aso-4 (87 ka) tephras were analyzed using an INAA scanning method. Source volcanoes for the five detected alkaline cryptotephra were identified from major element analyses of hand-picked glass shards: Ulleung (U–Ym, and the newly identified U–Sado), and Baegdusan (B–J, and the newly identified B–Sado and B-Ym). The eruption ages of the U–Ym, U–Sado, B–J, B–Sado, and B–Ymtephras are estimated to be 38 ka, 61 ka, 26 ka, 51 ka, 68–69 ka, and 86 ka, respectively, based on correlations with regional-scale TL (thinly laminated) layer stratigraphy (produced by basin-wide changes in bottom-water oxygen levels in response to millennium-scale paleoclimate variations). This study has allowed construction of an alkaline tephrostratigraphical framework for the late Quaternary linked to global environmental changes in the Japan Sea/East Sea, and improves our knowledge of the eruptive histories of Ulleung and Baegdusan volcanoes.

Detailed tephrochronologies are built to underpin probabilistic volcanic hazard forecasting, and to understand the dynamics and history of diverse geomorphic, climatic, soil-forming and environmental processes. Complicating factors include highly variable tephra distribution over time; difficulty in correlating tephras from site to site based on physical and chemical properties; and uncertain age determinations. Multiple sites permit construction of more accurate composite tephra records, but correctly merging individual site records by recognizing common events and site-specific gaps is complex. We present an automated procedure for matching tephra sequences between multiple deposition sites using stochastic local optimization techniques. If individual tephra age determinations are not significantly different between sites, they are matched and a more precise age is assigned. Known stratigraphy and mineralogical or geochemical compositions are used to constrain tephra matches. We apply this method to match tephra records from five long sediment cores (≤ 75 cal ka BP) in Auckland, New Zealand. Sediments at these sites preserve basaltic tephras from local eruptions of the Auckland Volcanic Field as well as distal rhyolitic and andesitic tephras from Okataina, Taupo, Egmont, Tongariro, and Tuhua (Mayor Island) volcanic centers. The new correlated record compiled is statistically more likely than previously published arrangements from this area.

Bed II is a critical part of early Pleistocene Olduvai Gorge, Tanzania. Its deposits include transitions from humid to more arid conditions (with associated faunal changes), from Homo habilis to erectus, and from Oldowan to Acheulean technology. Bed II (~ 1.8–1.2 Ma) is stratigraphically and environmentally complex, with facies changes, faulting, and unconformities, making site-to-site correlation over the ~ 20 km of exposure difficult. Bed II tuffs are thinner, less evenly preserved, and more reworked than those of Bed I. Five marker tuffs (Tuffs IIA–IID, Bird Print Tuff (BPT)), plus local tephra, were collected from multiple sites and characterized using stratigraphic position, mineral assemblage, and electron probe microanalysis of phenocryst (feldspar, hornblende, augite, titanomagnetite) and glass (where available) composition. Lowermost Bed II tuffs are dominantly nephelinitic, Middle Bed II tuffs (BPT, Tuff IIC) have basaltic components, and upper Bed II Tuff IID is trachytic. The BPT and Tuff IID are identified widely using phenocryst compositions (high-Ca plagioclase and high-Ti hornblende, respectively), though IID was originally (Hay, 1976) misidentified as Tuff IIC at Loc 91 (SHK Annexe) in the Side Gorge. This work helps establish a high-resolution basin-wide paleolandscape context for the Oldowan–Acheulean transition and helps link hominin, faunal and archaeological records.

The Pleistocene Humbu and Moinik formations of the Peninj Group in northern Tanzania preserve an important archaeological and paleontological record, in addition to a record of local volcanism in the form of tephra and lavas. Samples of the major Humbu and Moinik formations' basaltic and trachytic tephra were collected and characterized using phenocryst composition and both primary and authigenic mineral assemblage, since the volcanic glass was completely altered to zeolite. Some tephra are distinguishable solely using phenocrysts, but some are too similar in mineral composition or too poor in phenocrysts to definitively “fingerprint” without glass. Titanomagnetite phenocrysts were mostly altered; characterization was thus limited to feldspar, augite, and hornblende compositions for most tephra. Phenocryst compositions were compared to Olduvai tephra compositions to see if any regional tephra could be identified that could help correlate the sites. Augite or hornblende composition rules out potential correlations of Olduvai Bed I Tuff IF and the Bed II Bird Print Tuff or Tuff IID to otherwise similar Peninj Group tephra. Despite their overlap in age and locations at less than ~ 80 km from the Ngorongoro Volcanic Highlands, Peninj and Olduvai have different tephra records, which limits the possibilities for establishing a regional tephrostratigraphic framework.

Correlation of volcaniclastic deposits of the Bedded Tuff Member (K4) of the Kapthurin Formation (Kenya) provides the means to assess the nature of archaeological change during the later middle Pleistocene, a time period critical to human evolution but poorly represented at other African localities. Field stratigraphic evidence, and petrographic and electron microprobe geochemical analyses of volcanic glass and phenocrysts, define eight subdivisions of K4 tephra. These include a succession of deposits from a local volcanic source that erupted intermittently, as well as other tuffs likely from different sources outside the Baringo basin. Upper portions of the Bedded Tuff Member date to ∼235,000 yr. The Bedded Tuff Member is underlain by sediments that include the Grey Tuff, dated to 509,000 ± 9000 yr. The tephrostratigraphic framework defined here is used to place Acheulian and Middle Stone Age (MSA) archaeological sites in chronological order. Results show the persistence of Acheulian large cutting tool manufacture after the advent of points, considered an MSA artifact type. Two assemblages from the site of Koimilot record the appearance at ∼200,000–250,000 yr of a variety of Levallois flake production methods, an integral if incompletely understood feature of the MSA, here likely derived from local technological antecedents. Combined evidence from the tools and flake production methods suggest an incremental and mosaic pattern of change in hominin adaptive strategies during the Acheulian–MSA transition.

Paleoecological records from two Holocene peat bogs in northern Germany are linked by two microscopic volcanic ash layers, correlated by petrology and geochemistry to explosive volcanism on Iceland. The younger “Microlite tephra” cannot be correlated to any known eruption, while the older tephra layer is identified as a deposit of the Hekla 3 eruption. The tephra layers are dated by an age–depth regression of accelerator mass spectrometry 14C ages that have been calibrated and combined in probability distributions. This procedure gives an age of 730–664 cal yr B.C. for the “Microlite tephra” event and 1087–1006 cal yr B.C. for the Hekla 3 event. Accordingly, the tephra layers were deposited during the late Bronze Age. At this time, human settlement slowly increased pressure on the environment, as indicated by changes in woodland pollen composition at the two bogs. The tephra-marker horizons further show that the palynologically defined transition from the Subboreal to the Subatlantic Period is synchronous in the investigated area. However, the macroscopic visible marker in peat, the change from fibrous to sapric peat, the “Schwarztorf-Weißtorf-Kontakt,” is asynchronous. Bog vegetation did not immediately react in unison to a climatic change at this pollen zone boundary; instead, the timing of vegetation change depended on the location within the bog.

Stratigraphically important Quaternary rhyolitic tephra deposits that erupted from the Okataina and Taupo volcanic centers in New Zealand can be geochemically identified using the FeO and MgO contents of their biotite phenocrysts. The FeO/MgO ratio in biotite does not correlate with FeO/MgO in the coexisting glass phase so that tephra beds with similar glass compositions can be discriminated by their different biotite compositions. Some individual tephra deposits display sequential changes in biotite composition that allow separate phases of the eruption to be identified, greatly increasing the potential precision for correlation. In addition, devitrified lavas that are unsuitable for glass analysis can be correlated to coeval tephra deposits by their biotite compositions. Biotite is common in high-K2O (>4 wt%) tephra beds and is widely dispersed in ash plumes because of its platy form, thus making it important in correlation studies.

Single-grain geochemical composition of volcaniclastic sandstones can be a potential tool to improve correlations of mixed pyroclastic/epiclastic deposits. To test this, trachytic tuffs of the paleoanthropologically important FLK, FLK N, and FLK NN sites of Pleistocene Olduvai Gorge Bed I (Tanzania) are used as an established tephrostratigraphic framework against which to test volcaniclastic sandstone correlations. Fluvio-lacustrine sandstones and tuff samples were collected from eight archeological trenches between Tuffs IB and ID across a 500-m transect, including Leakey's famous Zinjanthropus (FLK) and OH 7/OH 8 (FLK NN) sites. A previously Tephrostratigraphy unknown, thin, fine, mineralogically unique, black trachyandesitic fallout ash was discovered below Tuff IC. Compositions of individual augite, feldspar and titanomagnetite grains from sandstones between Tuffs IB and IC reveal some IB-equivalent material, and a new compositional assemblage distinct from the sandwiching marker tuffs. Mineral compositions of the “tripartite” volcaniclastic sandstone between Tuffs IC and ID are similar to ID. Volcaniclastic sandstone grain fingerprints further refine correlations between fluvio-lacustrine sections within the area, providing support for proposed high-resolution stratigraphic reconstruction of the Zinjanthropus and OH 7/OH 8 land surfaces. This method might be applied to other sections where pyroclastic particles are admixed but distinct tuffs are not preserved.

Deposits from as many as 50 large tsunamis during the last 7000 years are preserved on the Pacific coast of the Kamchatka Peninsula near the mouth of the Zhupanova River, southern Kronotskiy Bay. These deposits are dated and correlated using Holocene marker tephra layers. The combined, preserved record of tsunami deposits and of numerous marker tephras on Kamchatka offers an unprecedented opportunity to study tsunami frequency. For example, from the stratigraphy along southern Kronotskiy Bay, we estimate frequency of large tsunamis (>5 m runup). In the last 3000 years, the minimum frequency is about one large tsunami per 100 years, and the maximum about one large tsunami per 30 years; the latter frequency occurred from about 0 to 1000 A.D. This time interval corresponds to a period of increased seismicity and volcanic activity that appears to be recorded in many places on the Kamchatka Peninsula.

A study of six tephra layers discovered in different deposits between 1600 and 2700 m a.s.l. in the Apennine chain in central Italy allowed precise stratigraphic constraints on environmental and climatic changes between ca. 4.5 and 3.8 cal ka BP. Chemical analyses allowed the correlation of these tephra layers with the eruptions of Agnano Mt Spina (AMST) from Phlegrean Field and Avellino (AVT) from Somma–Vesuvius. Major environmental changes in the high mountains of the Central Apennines occurred just after the deposition of the AMST and predate the deposition of the AVT. At this time, renewed growth of the Calderone Glacier occurred, marking the onset of the Apennine “Neoglacial”. The presence of the AMST and AVT enabled us to make a precise, physical correlation with other archives in central Italy. Synchronization of records between sites showed that the period intervening the deposition of the AMST and AVT layers coincided with environmental changes that were not always exactly in phase. This highlights the fact that stratigraphic correlations using only radiocarbon chronologies (the most common method used for dating archives during the Holocene) could produce erroneous correlation of events, giving rise to oversimplified paleoclimatic reconstructions.

At least twenty silicified volcanic ash beds have been identified in the Kuibis and Schwarzrand subgroups of the terminal Proterozoic Nama Group of Namibia. Nineteen of the Nama ash beds are in the Schwarzrand Subgroup in the Witputs subbasin. Two of these are in the siliciclastic-dominated lower part of the subgroup, which consists of the Nudaus Formation and Nasep Member of the Urusis Formation and comprises two depositional sequences. Identification and correlation of these ash beds are very well known based on stratigraphic position. Sixteen ash beds are contained within the carbonate-dominated strata of the Huns, Feldschuhhorn and Spitskop members of the Urusis Formation. These strata comprise four large-scale sequences and eighteen medium-scale sequences. Ash beds have been found in three of the large-scale sequences and seven of the medium-scale sequences. Correlations are proposed for these ash beds that extend over large changes in facies and stratal thickness and across transitions between the seaward margin, depocentre and landward margin of the Huns-Spitskop carbonate shelf. A study of whole rock and in situ phenocryst compositions was conducted to evaluate the feasibility of independently testing sequence stratigraphic correlations by geochemically identifying individual ash beds. Whole rock abundances of Al, Fe, Mg, K and Ti vary inversely with Si, reflecting variations in phenocryst concentration due to air fall and hydrodynamic sorting. These sorting processes did not substantially fractionate whole rock rare earth element abundances (REE), which vary more widely with Si. REE abundances are higher in samples of the Nudaus ash bed than in samples of the Nasep ash bed, independent of position in bed, phenocryst abundance, or grainsize, providing a geochemical means for discriminating between the two beds. Variations in the position of chondrite-normalized whole rock REE plots similarly support suspected correlations of ash beds between widely separated sections of the Spitskop Member. Abundances of Fe, Mg and Mn in apatite plot in distinct clusters for Spitskop ash beds that are known to be different and in clusters that overlap for ash beds suspected of correlating between sections. Abundances of REE in monazites differ for the Nudaus, Nasep and Spitskop ash beds in which these phenocrysts were identified. Multivariate statistical analysis provided a quantitative analysis of the discriminating power of different elements and found that whole rock abundances of Ge, Nb, Cs, Ba and La discriminate among the whole rock compositions of the Nudaus and Nasep ash beds and the Spitskop ash beds that are thought to correlate between sections. Each of the above geochemical signatures, by itself, is not definitive because the differences between beds are comparable to the variability within beds and because some signatures are shared by beds known to be different. Taken together, however, weight-of-evidence arguments based on multiple components and phases can successfully discriminate among Nama ash beds. Results from this study support sequence stratigraphic correlations of Spitskop ash beds that document stratal truncations and gaps in the record related to onlap and erosion.