As a result of interdisciplinary studies carried out on the Tersky coast of the White Sea, we have confirmed the existing ideas about the general trend of decreasing heights of the synchronous ancient coastlines in the eastern direction. We also revealed the age ‘mosaic’ structure of the marine terrace surface, which, according to our preliminary data, was formed as a result of at least two relative level rises of the White Sea – at the end of the Early – be-ginning of the Middle (~9.5–8.5 cal. kyr BP) and at the end of the Middle – beginning of the Late (~6.5–4.5 cal. kyr BP) Holocene, after which the shoreline smoothly moved to its present-day position.

We present new data that were generated by intensive field surveys and comprehensive geological-geomorphological, geophysical (ground-penetrating radar (GPR) profiling), paleolimnological and geoarchaeological studies within the top of the Unskaya Bay (the Letniy Coast of the White Sea) in 2020–2023. It was supplemented by radiocarbon dating and diatom analysis of the sediment cores from Chervozero and Svetloe Lakes (Una village area, Onezhskoye Pomorye National Park, Arhangelsk region), as well as interpretation of detailed space images. As a result, we reconstructed relative sea level (RSL) changes within the southern coast of the Unskaya Bay and its initial settlement by prehistoric humans in the Holocene. It was revealed that the late glacial transgression ended at an altitude of 9.8 m a. s. l. no later than ~ 10.3 thousand cal BP, at an altitude of ~ 8.5 m a. s. l. – no later than 10.0 thousand cal BP. The relative sea level didn’t exceed ~ 8.5 m a. s. l. during the Tapes transgression. The archaeologi- cal sites were facing the shores of an ancient strait that existed between the estuaries of the Unskaya and Ukhta Bays and were located at 9–10 m a. s. l.

We present new data of White Sea Coast dynamics within NE of the Gorlo Strait that were generated by satellite images, geomorphological and ground penetrating radar (GPR) profiling, aerial photography, and topographic surveys of coastal terraces and dunes. Our paleogeomorphological studies, supported by laboratory findings (diatom analysis and 14C dating), allowed us to reconstruct the morphodynamics of coastal and aeolian landforms. The obtained reconstruction enabled the evaluation of relative sea level (RSL) changes and the evolution of coastal landforms over the past 3.7 cal ka BP. According to our research, sand was supplied to coastal zone and coastal dunes through scarp erosion (0.5–3.7 m/year) as well as from the shoreface, while the role of alluvial runoff is insignificant. The largest dune massifs were formed in the areas of longshore drift (from NE to SW) discharge. At the mouth of the Maida River, the barrier spit and foredune plain have been evolving from the end of the Holocene transgression (∼3.7–2.3 cal ka BP). The mean high water at this time was slightly higher (up to ∼2.5 m a.s.l.), and coastal processes were significantly more intense than current ones. Then, against a decrease in sea level and weakening sediment flows, the growth of the spit slowed. The ancient foredunes were stabilized by vegetation. Aeolian processes were activated ∼2.1 and after ∼0.8–0.7 cal ka BP.

The late-glacial and post-glacial history of the development of the White Sea coastal zone in the area of the Varzuga River estuary is considered as a result of the interaction of endogenous and exogenous factors of coastal morpholithogenesis. Based on the geomorphological investigations, study of Holocene deposits by lithostratigraphic, diatom, and radiocarbon analyses, as well as collection and analysis of published data, new results on the development of relief of the area for 13 cal ka have been obtained. The features of the regional hierarchical morphostructure and local post-glacial tectonics of the territory—the spatial relationships of blocks and the rate of vertical movements—were determined. The superimposed linear Nizhnevarzugskaya Depression, which determined the configuration of the Varzuga River estuary in the late-glacial and post-glacial periods, was identified for the first time. The influence of the spatial ratio of blocks and differentiated post-glacial uplift on the coastal morpholithogenesis was established. The course of changes in the relative sea level (RSL), development conditions, and morphodynamics of the open coast and the estuary of the Varzuga River were reconstructed, and new data on the rhythms of coastal geomorphologic processes (coastal, estuarine, and eolian) were obtained. Three stages of development of the coastal zone were identified, which corresponded to regional rhythms of changes in the relative sea level and climate. They are (I) the Late Glacial transgression and Early Holocene regression ( 12 to 9.8 cal ka BP), (II) the Middle Holocene Tapes transgression (7.8 to 4.9 cal ka BP), and (III) the Late Holocene regression (after 4.9 cal ka BP). The upper marine boundary of the Late Glacial transgression was traced at heights of 54 or 55 m to the west of the Nizhnevarzugskaya depression, 39 or 40 m to its east, and 22 to 25 m a.s.l in the depression. The shores of lower morphostructural blocks up to 10.2–9.8 cal ka BP were probably blocked by dead ice. During the Tapes transgression, the RSL reached a maximum ( 20 m a.s.l.) of 7.8 to 7.6 cal ka BP and slowly decreased to 15 m a.s.l. in the interval of 7.6 to 4.9 cal ka BP. The prevailing directions of sediment fluxes and the approaches of winds and waves became similar to those of today and have not changed significantly since that time. The main source of the coastal sediment supply was the erosion of glaciofluvial sediments and the input of sands from the seabed. In the interval of 4.9 to 1.7 cal ka BP, the RSL decreased to 5 m a.s.l. and then slowly approached the modern one. Activation of coastal ( 5–1 cal ka BP) and channel ( 4.9–4.7 to 3.6–3.4 cal ka BP) processes contributed to rapid filling of the estuary and formation of accumulative sand terraces on exposed banks. The sediment runoff of the Varzuga River became the main source of coastal sediment supply. After 2.3 cal ka BP, several stages in the intensification of eolian processes were revealed.

On the southern coast of the Kola Peninsula, the relationship between meltwater and marine forma- tions at the mouths of the Olenitsa, Varzuga and Indera rivers was studied using geomorphological, ground penetrat- ing radar and paleolimnological methods. It has been established that below the «upper marine boundary», the sands of kamas and fluvioglacial deltas are completely or partially redeposited in the coastal zone. The contact between glacifluvial and marine sediments was recorded: at the mouth of the Olenitsa Rriver at ~ 40 m, on the right bank of the Varzuga River – 45 m, and between the mouths of the Varzuga and Indera rivers – 24–29 m a. s. l. Preliminary data from paleolimnological studies and 14C dating of bottom sediments of lakes Beloye (18.2 m а. s. l.), Chernoye (24.6 m а. s. l.), Gagarye (24.6 m а. s. l.) and «Eight» ( 26.2 m a. s. l.), suggest that the dead ice massif was per-sisted up to 11.4–11.1 cal. ka BP between the mouths of the Varzuga and Indera rivers. It prevented the penetration of Late-Glacial transgression waters into the lake basins and limited the possibility of the impact of coastal processes on glacial formations.

The relative sea-level changes for the time interval of ~12.1–9.1 ka cal BP were reconstructed on the eastern coast of the Gorlo Strait using the results of paleolimnological, GPR and geomorphological analyses conducted in the basin of the Srednyaya Tret’ Lake (7.3 m a.s.l., 66.014009° N, 41.086294° E), as well as UAV surveying of the lake surroundings. Bottom sediments of the lake were studied from the four core sections and correlated with each other according to the results of GPR data interpretation. Lithostratigraphic descriptions of bottom sediment cores, grain-size and diatom analyses, radiocarbon dating (AMS), determination of LOI, Corg content and Corg /Norg ratio were performed. We present the reconstruction of the coastlines at heights of 4–5 and 12–15 m formed by currents and/or wave processes within the lower Ruch’i River valley and Srednyaya Tret’ Lake according to field observations and interpretation of space images. As a result, the position of the relative sea-level and the chronology of the Late Glacial (Younger Dryas) transgression and the early stages of the Holocene (Tapes) transgression were refined. Late glacial transgression finished earlier than ~12.1 ka cal BP, and its relative level was probably no higher than 15 m a.s.l. After a deep regression, the relative sea-level approached the modern again ~9.5 ka cal BP, and at the Tapes transgression maximum (~9.1 ka cal BP) it was near the lake runoff threshold (∼5 m). Though the coastline was near the lake basin, sea waters never entered the lake. Sands, carried by the wind, accumulated in the part of the basin facing the coast. The the Srednyaya Tret’ Lake basin was gradually filled by fresh water according to the results of diatom analysis.

The relative sea-level changes for the time interval of ~12.1–9.1 ka cal BP were reconstructed on the eastern coast of the Gorlo Strait using the results of paleolimnological, GPR and geomorphological analyses conducted in the basin of the Srednyaya Tret’ Lake (7.3 m a.s.l., 66.014009° N, 41.086294° E), as well as UAV surveying of the lake surroundings. Bottom sediments of the lake were studied from the four core sections and correlated with each other according to the results of GPR data interpretation. Lithostratigraphic descriptions of bottom sediment cores, grain-size and diatom analyses, radiocarbon dating (AMS), determination of LOI, Corg content and Corg /Norg ratio were performed. We present the reconstruction of the coastlines at heights of 4–5 and 12–15 m formed by currents and/or wave processes within the lower Ruch’i River valley and Srednyaya Tret’ Lake according to field observations and interpretation of space images. As a result, the position of the relative sea-level and the chronology of the Late Glacial (Younger Dryas) transgression and the early stages of the Holocene (Tapes) transgression were refined. Late glacial transgression finished earlier than ~12.1 ka cal BP, and its relative level was probably no higher than 15 m a.s.l. After a deep regression, the relative sea-level approached the modern again ~9.5 ka cal BP, and at the Tapes transgression maximum (~9.1 ka cal BP) it was near the lake runoff threshold (∼5 m). Though the coastline was near the lake basin, sea waters never entered the lake. Sands, carried by the wind, accumulated in the part of the basin facing the coast. The the Srednyaya Tret’ Lake basin was gradually filled by fresh water according to the results of diatom analysis.

This study presents the results of lithological, diatom, geochemical analyses and radiocarbon chronology of the bottom lake sediments and peat bogs in the central part of the Onega Peninsula (the southern coast of the White Sea): Lake Maloye Murakanskoye (11.0 m a.s.l.), Lake Zhirovskoye (9.5 m a.s.l.), Lake Murakanskoye (7 m a.s.l.), and the Gorbovatiy Mokh bog (6.5 m a.s.l.). The bottom topography and sediments of Lake Murakanskoye were examined using sonar and ground penetration radar (GPR) survey, whereas in the other locations only the water depth was measured. Then, the digital models of the lake bottom topography were created. As an additional indicator of the relative sea-level (RSL) position, we used data on the altitude of the coastal terraces. Evidences of two transgressions in the White Sea (late glacial and Middle Holocene) are revealed. The transgressions were interrupted by two regressions (Early and Late Holocene). Our studies do not allow us to make a clear conclusion about the time and maximum level of the late glacial transgression. However, we may suggest that its level was above 11 m a.s.l. The regression of the Early Holocene started before 10.6-10.2 ka cal BP when the water level in the study area dropped below the altitude of 11m. At 9.4-9.1 ka cal BP the RSL was at an altitude of ca 7m. The Middle Holocene transgression (Tapes) started after 8.4 ka cal BP. The maximum level was reached before 7.4 ka cal BP and did not exceed an altitude of 9.5 m. The RSL stabilized at an altitude about 8.5-8 m during 7.4-6.0 ka cal BP. During 6.0-3.9 ka cal BP RSL very slowly decreased or fluctuated by the level of 8-7 m. RSL began to fall from the 7 m altitude about 4.0-3.9 ka cal BP and by 2.7-2.3 ka cal BP the sea-level reached 4.5 m. After that RSL dropped to its modern position. During the last 4.0 ka cal BP the rate of RSL fall was approximately 0.17-0.18 cm/year.

Fiard coasts are common on the periphery of the areas previously covered by ice sheets. The conditions in such areas are favorable for separation of bays and straits from the sea. As a result of the glacial isostatic adjustment of the area the fiards would be transformed into coastal lakes. To discover the regularities of evolution of such water bodies, we studied topography, sea and lake sediments, hydrology and diatom associations of meromictic Lake Kislo-Sladkoe at the Karelian Coast of the Kandalaksha Bay, the White Sea, Russia (66°32′54″N, 33°08′05″E). Detailed geomorphological, geodetic, bathymetric, and aerial imagery field works have been completed on the coastal area. We built a Digital Elevation Model (DEM) of the coast and seabed. Radioisotope dating (210Pb, 14С), grain size distribution, loss on ignition, Corg/Norg ratio and diatom analysis have been completed for the entire 1.5-m sequence of the Lake's sediments. Currently, the Lake Kislo-Sladkoe communicates with the sea through a rising sill. We have established that the water body is meromictic due to its upper water layer being of variable salinity, middle layer comprising of aerated salty water, and the near-bottom water layer being anaerobic. However, several-year-long periods of water stratification alternate there with occasional late-autumn or early-winter flushes. The water body evolution falls into four stages: (1) a strait with an active hydrodynamic environment (prior to 1500–1560s), (2) a strait with a variable hydrodynamic environment (1500–1560s to 1850–1890s), (3) a semi-isolated lagoon with a quiet hydrodynamic environment (1850–1890s to early 1950s), and (4) a meromictic lake at an early stage of separation from the sea (early 1950s to present). We show how coastal processes on fiard coasts change the mode and duration of isolation of coastal water bodies from the sea. Based on the assessment of the rate of the post-glacial rebound and hydrological conditions of the coastal area we propose an approach to estimating the duration of transitional phase between a marine bay or strait and freshwater lake, including its meromictic stage. We predict that the meromictic stage of the lake will be completed no earlier than c. 100–200 years after the sill rises above the tidal zone.

Abstract. Geomorphological, ground penetration radar profiling and paleolimnological investigations were carried out in the Lake SrednyayaTret (66.014009 N, 41.086294 E; 7.3 m ASL). Bottom sediments from the three boreholes were studied. Lithologostratigraphic description, grain-size and diatom analyses were carried out, loss on ignition, Corg/Nogr was determined. Radiocarbon ages were obtained from the lower horizons of post-glacial sediments. Signs of Late Glacial transgression (earlier ~12.1 kyr. cal. BP) and Early Holocene regression (started between ~12.1 and ~10.3 kyr. cal. BP) were determined. The next filling of the lake basin can be compared with the Middle Holocene transgression. At the same time sea waters did not penetrate into the lake basin. The beginning of this stage was apparently accompanied by intensification of coastal aeolian processes.

An overview of the Late Pleistocene and Holocene stratigraphy of the southeastern White Sea region is presented in the paper, based upon the analysis of published data, new results, and correlation between marine and terrestrial archives. The Pleistocene stratigraphic record in the southeastern White Sea region begins with Mikulino Horizon, which comprises the whole MIS 5 and is composed of marine sediments – sands, sandy clays and clays – with Boreal, Arctic–Boreal and Lusitanean–Boreal microfauna and mollusc fauna, dated back at 161–77 ka. The Podporozhie Horizon in the southeastern White Sea region comprises the MIS 4 (71–57 ka) complex of marine mostly near-shore sediments. The glaciation during MIS 4 was localized, on one hand, within the Kola Peninsula. On the other hand, the glacier probably overlapped the Kanin Peninsula and the Mezen Bay, however the Gorlo Strait was not blocked and the northward river outflow was preserved. The Leningrad Horizon had been formed also in the marine sedimentation pattern during the MIS 3 (57–29 ka). However, the lack of data in the region allows us to make only the comparative analysis. The Ostashkov Horizon (MIS 2, 29–11.7 ka) is composed of the deposits of glacial paragenetic series: tills, glaciofluvial, glaciomarine, and glaciolacustrine deposits, but also comprises the deglaciation (Late Glacial) sedimentary complex including marginal tills. The Holocene stratigraphic record is subdivided into three stages – 11.7–9.5, 9.5–3.5 and 3.5–0 ka BP, and do not match with new formal stratigraphic subdivision of the Holocene series.

We present the preliminary results of the granulometric and geochemical analyses of lake-bottom sediments obtained from the Murmanskoe and Maloe Murmanskoe lakes. Based on the collected data, we reconstructed changes of relative sea-level (RSL) in the Gulf of Dvina (White Sea) during the Holocene. The conditions and maximum levels of two transgressions (Late Glacial and Tapes) and one Early Holocene regression were identified.

An overview of 16 sites of coastal erosion monitoring at the fastest retreating key sites across the Russian Arctic was made. All of these coasts are composed by permafrost, creating specific conditions of their evolution and making them very sensitive to sea ice reduction and ice-free period increase along with the temperature growth, resulting from the ongoing climate change. Erosion of permafrost coasts is among the fastest destructive geomorphic processes in the Arctic. For each key area, data from literature on sediment composition, coastal morphology, permafrost properties and climate evolution were collected, assessed and compared. Rates of coastal retreat in the XX-XXI century derived from direct field measurements and processing of remotely sensed data were analyzed; mechanisms and drivers of coastal erosion were estimated. Patterns of spatial variability and temporal evolution of the coasts were suggested. The influence of different factors of coastal dynamics on thermodenudation (destruction of the bluffs during thawing of permafrost and ground ice) and thermoabrasion (erosion resulting from direct contact of waves with the frozen bluff) was estimated.

The coastal zone of the Arctic seas is characterized by high dynamics due to the presence of permafrost. In SW part of the Kara Sea the coastal cliffs are composed of frozen unlitified deposits. Massive ice beds and ice wedges are widespread on various absolute heights. In this region, the coastal erosion rates are 0.5 to 2 m.a(-1). At the points where high cliffs have massive ice beds inclusions and low cliffs experience great storm events, erosion rates may rich 7-14 m.a(-1). The coastal retreat rates have a lognormal distribution. In order to understand the destruction processes on the key sites, numeric simulations were performed. The model is based on the heat balance equation and the Stefan approach. Boundary conditions were set based on climatic parameters obtained according to the weather station (Marre-Sale). According to this data, two different periods can be identified: with a higher thermal action in 1995-2017, and a lower in 1973-1995. For these periods, numerical simulation of the coastal retreat was made. The physical parameters of the sediments applied for the simulations were derived from laboratory tests and literature The lithological composition varies from loamy clays and silts to gravel sands. Since thermodenudation causing erosion rate strongly depends on slope deposits removal process, different regimes of removal of the thawed layer were simulated. The crucial influence of slope cleaning mode, ice content in the soils and their reaction under climate changes on the erosion rates were demonstrated. Observed and simulated results correlate well.

The distribution of diatoms in the core of bottom sediments of the small meromictic Lake Kislo-Sladkoe on the Karelian Coast of White Sea was studied. The changes in diatom associations in the column show the isolation of the lagoon from the sea and its transformation into a meromictic lake. First alteration of dominant species marks the decrease of hydrodynamic activity as a result of the formation of spit and transformation of the lagoon into semi-closed bay. Second shift in species composition reflects the onset of the strong stratification and occurrence of a bottom anoxic layer.

Впервые выполнены диатомовый анализ и радиоуглеродное датирование осадочного чехла террас юго-восточного побережья Горла Белого моря на участке мыс Вепревский-мыс Инцы. Распространение голоценовых морских отложений прослежено до абсолютной высоты 4 м. Повышение относительного уровня моря происходило на протяжении бореального и первой половины атлантического периодов. Уровень моря достиг современного не ранее 8,5 тыс. ( 14 С) л.н., а ~6,3 тыс. ( 14 С) л.н., вероятно, стабилизировался на отметках 3,5-4,0 м. Регрессия и переход от морского к континентальному осадконакоплению на этих высотах датируются ~3 тыс. ( 14 С) л.н. Более высокие уровни сформировались ранее 9,5-8,5 тыс. ( 14 С) л.н. и, по данным диатомового анализа, позднее не затапливались морем. Во время раннеголоценовой регрессии на них формировались горизонты, интерпретируемые как палеопочвы. Они перекрыты озёрными, болотными и эоловыми отложениями.

В статье представлены результаты диатомового анализа донных отложений оз. Щучьего, расположенного на Кольском п-ове в северной части Хибинского горного массива. Данные радиоуглеродного датирования и сопоставление с опубликованными ранее разрезами озерных отложений Кольского п-ова позволяют сделать вывод, что накопление донных отложений оз. Щучьего началось на заключительных этапах дегляциации в начале голоцена и продолжалось непрерывно до настоящего времени. По изменениям концентрации, видового разнообразия и видового состава диатомовых ассоциаций выделено 8 диатомовых зон. Изменения в составе диатомовых ассоциаций донных отложений отражают изменения гидродинамического режима озера, связанные с изоляцией от оз. Гольцового и влиянием стока р. Кунийок, а также сукцессионные процессы на его водосборе: заболачивание и вариации интенсивности эрозионного и селевого сноса, связанные с изменением характера растительности. Климатические изменения в голоцене запечатлелись как непосредственно в изменении процентного содержания индикаторных видов, так и опосредованно через колебания рН и т. д. Раннеголоценовое потепление в Хибинах началось позднее, чем в прибрежных районах. Это может быть связано с особенностями дегляциации: более поздним таянием ледников в пределах горных массивов. Наряду с эволюционными изменениями природной среды в донных отложениях оз. Щучьего отражены некоторые события катастрофического характера, в том числе, вероятно, селевые процессы, обусловившие формирование четко выраженного прослоя терригенного материала в органогенных отложениях в верхней части разреза. Так, на ранних этапах существования озера отмечается привнос большого количества терригенного материала, очевидно, в результате эрозионного и селевого сноса с незакрепленных склонов в условиях разреженной растительности.