Rhizoliths, cylindrical concretions formed primarily by CaCO3 accumulation around plant roots, serve as valuable indicators of past environmental conditions, including hydrology, redox dynamics, and carbon cycling. Despite growing interest in paleo-reconstructions, the lack of quantitative studies on formation mechanisms complicates interpretation. We present “RhizoCalc”, the first mechanistic model (deployed in HYDRUS-1D) computing rhizolith formation in CaCO3-containing loess soils, integrating water fluxes, root water uptake, and (Ca)-carbonate chemistry to simulate conditions under which rhizoliths develop. Hydraulic fluxes drive Ca2+ transport (0.13–1 mmol/L) toward the rhizosphere, governed by root water uptake under low (ETo = 0.03 cm/d) and high (ETo = 1 cm/d) flow rates at optimal (ho = –100 cm) and intermediate (ho = –1000 cm) moisture conditions. The simulations show that hydraulic constraints and calcite-induced jamming of the porous medium are key inhibitors of rhizolith growth, distinguishing physical limitations from biogeochemical feedbacks in the rhizosphere. On top of this, our work reveals root encasement and reliquary varieties, linking their physical and biogeochemical mechanisms to rhizolith transformations and offering insights into paleosol hydrology and redox dynamics. Under intermediate soil-water conditions with 1 mmol/L Ca2+, concentric rhizoliths with 0.2–3 cm radii form chrono-sequentially over 1.5–150 years. Each layer preserves CaCO3 constituents (δ18O, δ13C, 44Ca, 46Ca, 48Ca), root-derived biomarkers (e.g., lignin), and clumped isotopes (Δ47), preserving environmental signatures across time into the future. Therefore, this framework conceptualizes each rhizolith as a ‘time-capsule’ with each successive CaCO3 layer encapsulating a snapshot of vital environmental proxies, providing a window into otherwise inaccessible historic ecosystem dynamics. Refining reconstructions of Earth’s paleoclimatic history requires cross-sectional isolation of concentric layers in well-preserved rhizoliths, capturing distinct isotopic bands and their stratigraphy.

The central European loess-paleosol sequence (Marine Oxygen Isotope Stage (MIS) 6–2) at three sites located in northwestern Ukraine, in the transitional area between the oceanic and continental climates, has been studied using micromorphological, grain-size, pollen, and magnetic methods. The sequence is characterized by a well-developed pedocomplex S1 (correlative of MIS 5), comprising four soils, and three interstadial soils within loess L1 (MIS 4–2). The soils of S1 are synsedimentary, indicating a dynamic depositional environment with pulses of aeolian sand sedimentation from late MIS 6 to MIS 5a. From various cryogenic features, the permafrost aggradation for MIS 6, 4, and 2, and deep seasonal freezing for MIS 5d and 5b were reconstructed. Distinct redoximorphic features of the loess units, widespread solifluction, well-developed periglacial phenomena, and very low magnetic susceptibility values for the loess-paleosol sequence of northwestern Ukraine reveal its similarity to those of the central European loess subdomain of the northern European loess belt. The low concentration of ferrimagnetic minerals in the parent material and intensive processes of physical and chemical weathering are reflected in the specific model of magnetic enhancement of the studied sequence, which is transitional between the “Chinese” (pedogenic) and “Alaskan” (reducing-pedogenic) models.

The multi-layered settlement of Turganik in the Tok River valley (steppe region west of the Urals) has been studied using paleopedological and microbiomorphical methods. Early humans lived in the settlement during the Eneolithic epoch (the fifth millennium BC) and in the Early Bronze Age (the fourth millennium BC). The cultural layers attributable to the Atlantic period of the Holocene developed under conditions of a rather dry climate, with the landscapes being dominated by the grass and herb steppe. The settlement area was above the flood water level and was suitable for habitation. The soils in its vicinity were Kastanozems (Endosalic Protosodic). The final stages of the cultural layer formation bear traces of strong (though short-term) floods, with the deposits of the latter partly concealed traces of the preceding long-term arid phase. Maximum aridity was during the final interval of the Atlantic period. The Subboreal and Subatlantic periods were noted for meadow-chernozem soil formation (Luvic Chernozems [Stagnic]) and an increasing proportion of arboreal species in the pollen assemblages. Some phytoliths of aquatic plants were found in the assemblages dominated by those of meadow grasses. The climate was more humid and cool, although short episodes of aridity were possible.

Holocene climatic variability and human impact on vegetation are reconstructed from a region in central European Russia, which lies at an important ecotone between broadleaf forest and steppe. For the first time in this region we adopt a multi-proxy approach that combines analysis of local mire conditions from plant macrofossil and testate amoeba analyses with pollen-based quantitative climate reconstruction. The proxies indicate a long-term warming trend from 9700 to 7500 cal yr BP, interrupted by a series of short-term cold events. From 7500 to 5000 cal yr BP the results imply a relatively stable climate, warmer and drier than present, spanning the Holocene Thermal Maximum. Since 5000 cal yr BP the data suggest a change to cooler climate, but with centennial-scale variability. This shift at around 5000 cal yr BP is supported by extensive evidence from other sites. In the early Holocene, the region was occupied mainly by pine and birch forests. Broad-leafed forests of oak, lime and elm expanded after 7800 cal yr BP and remained dominant until the last few centuries. During the historical period, vegetation changes have been driven mainly by human activities.

Two fundamental issues for tephrostratigraphic work are the differentiation of primary from reworked tephra and the characterization of reworking mechanisms. We study the depositional processes of four deposits of Youngest Toba Tuff in the Lenggong valley, Malaysia. We focus on site stratigraphy, particle-size distributions, magnetic susceptibility and mineralogical associations. Reworked tephra display variable sedimentological characteristics including polymodal and unimodal, very fine to coarse-grained distributions, and variable concentrations of ash. Particle-size distributions from this study are similar to published analyses for primary deposits, demonstrating that particle size alone cannot distinguish primary from secondary tephra. The tephra sequences are associated with fluvial and colluvial deposition. Three facies are identified: flood flow, mudflow and slumping. The ash accumulated rapidly, over a period of a few days to months. In this valley the ideal site for paleoenvironmental reconstructions is Kampung Luat 3, where ash accumulated at least in two distinct phases. Despite the rapid accumulation, the Lenggong sites are not well-suited for paleoenvironmental studies of the YTT impact. The time lag between the primary deposition and the floods is unknown and the records could have been modified by site-specific characteristics. Such variables should be considered when proposing paleo-environmental reconstructions based on reworked tephra.