Discussion on ‘Deglaciation and neotectonics in SE Raasay, Scottish Inner Hebrides’ by Smith et al. 2021 (SJG, 57, xx-yy)

I congratulate David Smith and his colleagues (2021) on an excellent presentation of their work on the evolution of the morphology and events involved in the evolution of the Beinn na Leac area in south-east Raasay. The summit area is a difficult and even dangerous area to work in, as I know from personal experience – learning to only follow sheep tracks to avoid the many deep fissures with openings often hidden by vegetation.

The lichens of the Majella National Park (Central Italy): an annotated checklist

The botanical exploration of the Majella National Park has a long tradition dating back to the eighteenth century. However, the lichen biota of this area is still poorly investigated. To provide a baseline for future investigations, in this annotated checklist, we summarised all available information on the occurrence of lichens in the Majella National Park, retrieved from previous literature, herbarium material and original data produced by recent research. The checklist includes 342 infrageneric taxa. However, seven taxa are considered as dubious, thus setting the number of accepted taxa at 335, i.e. 45.8% of those currently known to occur in the Abruzzo Region. This checklist provides a baseline of the lichens known to occur in the Majella National Park, highlighting the potential of this area as a hotspot of lichen biodiversity, especially from a biogeographical point of view as indicated by the occurrence of several arctic-alpine species that form disjunct populations in the summit area of the massif.

The timing of deglaciation from mountain summits to cirques in Wales: 10Be and 26Al exposure dates from Cadair Idris

<p>Cosmogenic <sup>10</sup>Be and <sup>26</sup>Al exposure ages from 20 erratic samples collected from Cadair Idris (893 m), a mountain in southern Snowdonia, Wales, provide evidence for the timing of deglaciation from summits to cirques at the end of the Late Pleistocene. The summit of the mountain is characterised by intensely modified frost-shattered surfaces that have long been identified as a representing a former nunatak. Numerous glacially-transported quartz boulders on the highest ground indicate that ice overran the summit at some point in the Pleistocene. Two quartz boulders, one with preserved striations, sampled at c. 856 m near the summit of Cadair Idris yielded consistent <sup>10</sup>Be and <sup>26</sup>Al paired exposure ages of 75 ka to 60 ka (using a high-latitude sea level <sup>10</sup>Be spallation production rate of 4.20 at/g/y, scaled by the Lal/Stone scheme). A glacially polished bedrock quartzite outcrop at 735 m gave an age of 17.5 ka. Immediately below this, cirque and down-valley recessional moraine ages, covering an elevation of 480 m to 350 m ranged from 10 to 15 ka respectively.</p><p>These results confirm that Cadair Idris was overridden by the Welsh Ice Cap during marine isotope stage (MIS) 4, when ice was thicker than at the global last glacial maximum (LGM) in MIS 2. This is consistent with findings from northern Snowdonia. The highest Welsh summits, including Cadair Idris, emerged above a thinning Welsh Ice Cap (British Irish Ice Sheet) during the transition from MIS 4 to 3. The summit area above ~800 m then stood as nunataks above the LGM ice sheet surface in MIS 2. The Welsh Ice Cap then rapidly thinned over Cadair Idris at ~20-17 ka based on ages from high-level ice-moulded bedrockThis is supported by more new ages from high-level paired erratics and bedrock samples on several other mountains throughout Snowdonia, leading to a phase of alpine-style deglaciation. Valley glaciers initiated their retreat up-valley from ~17 to 14 ka after Heinrich Event 1. A later phase of glacier stabilisation or still stand formation produced classic cirque moraines near the rim of a present cirque lake basin (480 m elevation) yielding <sup>10</sup>Be ages of 13-10 ka during the Younger Dryas.</p>

Efeitos da dinâmica pluviométrica na interceptação e precipitação interna em uma encosta com Floresta Atlântica no Parque Nacional da Tijuca, RJ, Brasil

Given the importance of vegetation cover for the hydric balance, the present paper aimed to analyze the pluviometric dynamics for the net precipitation and interception process, in the forested hillslope in the Tijuca National Park. The influence by a set of independents variables given by hydrometeorological dynamics (rainfall volume and intensity and drought context) was discussed face the temporal modulation for interception and net precipitation, coupled a spatial analyze given by comparisons between hillslope positions (summit; upper hillslope; lower hillslope; valley bottom), where there is a vegetation structure heterogeneity originated by geomorphological context. The volume intercepted at each event varies directly proportional to the antecedent drought time, with the complementary effect of the rainfall volume in the previous 15-days. The percentual interception varies inversely proportional to the gross precipitation and its intensity. It is about the interception wich best manifests the significance of the spatial variations, with highlights for the summit área, where the canopy openness is bigger. The net precipitation varies under the strong influence – directly proportional – by gross precipitation volumes, being better explained with the complementary effect by the previous drought. The spatial variations on the net precipitation are less significant in comparison to the interception, decreasing the significance in the time of increase of the gross precipitation volumes.

Hydrothermal Activity at a Cretaceous Seamount, Canary Archipelago, Caused by Rejuvenated Volcanism

Our knowledge of venting at intraplate seamounts is limited. Almost nothing is known about past hydrothermal activity at seamounts, because indicators are soon blanketed by sediment. This study provides evidence for temporary hydrothermal circulation at Henry Seamount, a re-activated Cretaceous volcano near El Hierro island, close to the current locus of the Canary Island hotspot. In the summit area at around 3000–3200 m water depth, we found areas with dense coverage by shell fragments from vesicomyid clams, a few living chemosymbiotic bivalves, and evidence for sites of weak fluid venting. Our observations suggest pulses of hydrothermal activity since some thousands or tens of thousands years, which is now waning. We also recovered glassy heterolithologic tephra and dispersed basaltic rock fragments from the summit area. Their freshness suggests eruption during the Pleistocene to Holocene, implying minor rejuvenated volcanism at Henry Seamount probably related to the nearby Canary hotspot. Heat flow values determined on the surrounding seafloor (49 ± 7 mW/m2) are close to the expected background for conductively cooled 155 Ma old crust; the proximity to the hotspot did not result in elevated basal heat flow. A weak increase in heat flow toward the southwestern seamount flank likely reflects recent local fluid circulation. We propose that hydrothermal circulation at Henry Seamount was, and still is, driven by heat pulses from weak rejuvenated volcanic activity. Our results suggest that even single eruptions at submarine intraplate volcanoes may give rise to ephemeral hydrothermal systems and generate potentially habitable environments.

The 2019 Stromboli eruption: the space-borne and ground-based InSAR contribution

<p>On 3 July 2019, Stromboli experienced a paroxysmal explosion without long-term precursors, as instead occurred before the last two effusive eruptions. In the following months, lava outpoured from a vent localized in the SW crater area, and sporadically from the NE one. On 28 August 2019, a new paroxysmal explosion occurred, followed by strong volcanic activity, culminating with a lava flow emitted from the SW-Central crater area. Subsequently, the eruptive activity decreased, although frequent instability phenomena linked to the growth of new cones on the edge of the crater terrace occurred. This contribution summarizes the measurements obtained through space-borne and ground-based InSAR sensors. The ground-based data allowed to detect pressurization of the summit area, as the instability of the newly emplaced material. The satellite data instead helped to identify the slope dynamics. The integration of the complementary systems strengthens the monitoring of both the eruptive activity and the instability phenomena.</p><p>This work is supported by the 2019-2021 Università di Firenze and Italian Civil Protection Department agreement, and by the 2019-2021 IREA-CNR and Italian Civil Protection Department agreement.</p>

Glaciovolcanic emplacement of an intermediate hydroclastic breccia-lobe complex during the penultimate glacial period (190–130 ka), Ruapehu volcano, New Zealand

An intermediate-composition hydroclastic breccia deposit is exposed in the upper reaches of a deep glacial valley at Ruapehu volcano, New Zealand, indicating an ancient accumulation of water existed near the current summit area. Lobate intrusions within the deposit have variably fluidal and brecciated margins, and are inferred to have been intruded while the deposit was wet and unconsolidated. The tectonic setting, elevation of Ruapehu, and glacial evidence suggest that the deposit-forming eruption took place in meltwater produced from an ancient glacier. The breccia-lobe complex is inferred to have been emplaced at > 154 ± 12 ka, during the penultimate glacial period (190–130 ka) when Ruapehu’s glaciers were more extensive than today. This age is based on overlying radiometrically dated lava flows, and by correlation with a well-constrained geochemical stratigraphy for Ruapehu. Field relations indicate that the glacier was at least 150 m thick, and ubiquitous quench textures and jigsaw-fit fracturing suggest that the clastic deposit was formed from non-explosive fragmentation of lava in standing water. Such features are unusual for the high flanks of a volcanic edifice where steep topography typically hinders accumulation of water or thick ice, and hence the formation and retention of hydroclastic material. Although not well-constrained for this time, the vent configuration at Ruapehu is inferred to have contributed to an irregular edifice morphology, allowing thick ice to locally accumulate and meltwater to be trapped.

Installation of New GNSS Network Around Kusatsu-Shirane Volcano, Japan: Its Perspective and the First Result

Crustal deformation is essential information for monitoring volcanic activity. In the summit area of the Kusatsu-Shirane Volcano (KSV), a dense Global Navigation Satellite System (GNSS) network has been operating near the recent volcanic center, Yugama crater. This network is sensitive to shallow depth activity, such as phreatic eruptions at the summit area, but is not applicable to deep magmatic activity, suggested to have been occurring for thousands of years by recent geological studies. Aiming to detect magmatic activity at a certain depth, we installed a new GNSS network near KSV. The observation sites were selected based on the crustal deformation pattern calculated for several intrusive events of the deep-seated magma. First, the GNSS sites for campaign observation were installed at eight locations in 2017. Then, four continuous sites commenced operation after a phreatic eruption at Mt. Motoshirane in January 2018. Here, we show the results of the first and second observation campaigns, operating in October 2017 and February 2018. Coordinate values are computed by precise point positioning with ambiguity resolution (PPP-AR) analysis and are used to calculate the displacement and the baseline length change during this period. The uncertainties of the calculated coordinate values are sufficiently small (less than 4.5 mm) except at some sites for which the data possibly include multipath errors due to trees and snow. Although any deformation associated with the 2018 eruption of Mt. Motoshirane is not detected, subsequent observations would contribute to monitoring long-term activity near KSV.

Increasing Summit Degassing at the Stromboli Volcano and Relationships with Volcanic Activity (2016–2018)

The last increased volcanic activity of the Stromboli volcano, from 2016 to 2018, was characterized by increases in the number and frequency of crater explosions and by episodes of lava overflow. The volcanic activity was monitored utilizing CO2 soil fluxes acquired from the Stromboli summit area (STR02 station). To better understand the behavior of the shallow plumbing system of the Stromboli volcano in the period of 2016–2018, we utilized a large data set spanning from 2000 to 2018. The data in this last period confirm a long growing trend of CO2 summit degassing, already observed in the years since 2005 (reaching 23,000 g·m−2·d−1). Moreover, within this increasing trend, episodes of sudden and sharp increases in the degassing rate, up to 24.2 g·m−2·d−2 were recorded, which are correlated with the observed paroxysmal activity (increased summit explosions and overflow).