A New Interpretation of Ptolemy's Germania Magna: Employing Computer-Assisted Image Distortion of a Medieval Map by Donnus Nicolaus Germanus to Examine Post-Glacial Geodynamics in Europe

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This is an older dataset that has been replaced by a newer version of this work. You can find the current one at doi: 10.5281/zenodo.10968193

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Note about the Germania Magna Research Project on Zenodo:

This contribution to the repository presents the current main publications of the geodynamic modelling project. As part of an actively evolving model, its content adapts to the current development stage and serves as the project’s central version control and documentation platform. The model is progressively advancing from an initially descriptive approach toward a more rigorous mathematical, geometric, and cartometric formalisation.

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The v7 Geodynamic Model Description for Ptolemys Germania Magna

based on (Mildner, S. (2026). Geodynamic Reinterpretation Model for Ptolemy’s Germania Magna: General Model Description, Cartometric Foundations, (v7.1). EarthArXiv (Preprint). https://doi.org/10.31223/X5KB51)

The reconstruction of spatial coordinates from Claudius Ptolemy’s Geographike Hyphegesis (c. 150 AD) for Central Europe has historically been hindered by significant and spatially autocorrelated residual errors. While the traditional cartographic consensus attributes these discrepancies primarily to cumulative human measurement errors or medieval copyist distortions, this paper introduces and successively refines an alternative, quantitative methodology based on kinematic block-deformation modelling. Using GIS-anchored affine transformations, a rigidly constrained multi-parameter framework (k ≈ 27.0 km/°P) is established incorporating geometric scaling, hydrographic topological anchors, and structural block kinematics.

Rather than treating coordinate shifts as arbitrary map distortion, the model tests the mathematical coherence of treating the Elster-Lusatia geographic cluster as a translation-glide block relative to a rigid Lausitz backstop. With the Leukaristos (Finsterwalde), Arsonion (Senftenberg zone), and Carrodunum (Kamenz/Spreetal area) identifications added in v7, the statistical test yields t = −19.1, p ≪ 0.001, df = 5 - firmly ruling out uniform measurement error. The Arsonion identification localises the Décollementabscherfront (Zechstein décollement tip), completing the kinematic picture of beginning, propagation, and arrest of the translation. The model simultaneously identifies the Sudete Mons / Thüringer Wald as a rigid-rotation block (dextral +35° about the geometrical Waltershausen pivot (initially determined approximately), 10°33′E / 50°53′N, inter-endpoint distance preserved within 2 %).

The structural coupling between the fragmentation of the Abnobae Mons and the sharp buckling of the Main Valley in this v7.1 model is based on a direct mechanical interaction between extension (transtension) in the north and compression in the south, operating around this geometrical Waltershausen Pivot as the central hinge (pp. 2, 43). This system can be visualised as a giant shear or opening wedge mechanism.

1. The Northern Extensional Centre: The Vogelsberg Pull-Apart

The triggering impulse stems from the hypothetical Český Kráter impact (Bramsche as a passive structure in the north) and its associated shock waves, which induced counter-rotating block movements. While the Thuringian Forest (Sudete Mons) underwent dextral (clockwise) rotation, the southern Abnobae block responded with sinistral (counter-clockwise) rotation and southeastward (ESE) displacement (pp. 2, 30–31). Between these diverging units, a major zone of crustal stretching developed. In the Vogelsberg–Wetterau region, the crust ruptured in a parallelogram-shaped pull-apart basin (pp. 2, 4). This deep-seated rift was filled with magmatic material — the Miocene basalts — which were later phreatomagmatically reactivated during the 6th-century event (pp. 2, 31).

2. The Southern Compressional Centre: The Main Valley Kink Zone

A crustal block cannot rotate in isolation without generating significant boundary stresses. As the southern portion of the Abnobae block (including the Odenwald and Spessart) moved ESE, it acted like a rigid indenter, exerting strong pressure against the stable foreland to the south and east (pp. 2, 30). The Main Valley lies exactly at the focal point of this rotational push and the simultaneous WNW-directed shock wave emanating from the Český Kráter impact (pp. 40, 43). Acting as a transpressional transfer node and elastic buffer zone (pp. 4, 11), the originally relatively straight course of the proto-Main (Ptolemy’s Danubius) was unable to withstand the combined stress. It deformed plastically, developing kink folds that produced the characteristic orthogonal bends of the Main Triangle (Maindreieck) and Main Square (Mainviereck) (p. 43).

Version 7 introduces three structural improvements that further constrain the framework. First, the Ptolemaic Abnoba Mons is re-identified as a coherent pre-deformation crustal block encompassing the modern Taunus, Odenwald, Spessart, Rhön, and pre- Vogelsberg basement; fragmentation into separate modern ranges results from a ∼−22° sinistral rotation of the southern portion about the same Waltershausen pivot that drives the Thuringian Forest. In structural geology, the near-equality of lever arms originating from a single central root, combined with opposite senses of rotation (CW and CCW) in adjacent blocks, is the definitive geometric signature of a positive flower structure. The area SW of Waltershausen pivot represents the deep crustal root of a massive, regional transpressional extrusion zone. The geometrical pre-deformation positions of the Rhenus Fluvius source near (∼8.60°E / 50.06◦N) and the Danubius Fluvius source near (∼8.96°E / 50.07°N) lie only ∼26 km apart — in precise agreement with the Mercator (1569) cartographic representation. Second, internal proportions in Ptolemy’s coordinate system independently corroborate the Vistula = Lausitz identification: the Ptolemaic Harz–Vistula longitude ratio predicts a real-world distance of ≈325 km, which matches the Oder mouth (≈300 km) and rules out the Polish Vistula (≈620 km) as a 2× map stretch.

Third, the trigger budget is revised on physical grounds: direct down-range coupling between the Saale-Unstrut impact lobe and the pre-shift Elster-Cluster positions makes SU the dominant translation driver (≈50%), with Český Kráter contributing ≈35%, Africa/CDF ≈10% (primarily pre-loading), and Bramsche ≈5%. Explicit, falsifiable criteria are defined through 34 specific tests (T1–T34), including OSL dating, reflection-seismic profiling, 40Ar/39Ar age-gradient testing across the Vogelsberg, direct cartometric matching of Ptolemaic Rhenus/Danubius source coordinates, and isotope-hydrogeological confirmation of the Ottendorf-Okrilla Vistula Fluvius source.

The historical geography of Germania Magna is methodologically among the most demanding fields of classical studies and geodetic research. The currently dominant reference model (statistical-geodetic rectification of the TU Berlin group) explains deviations between Ptolemaic coordinates and modern topography primarily as measurement errors of ancient instruments or as transmission artefacts. The present work opposes this concept on two fronts: (i) the primary explanatory principle is the recognition that the northern reference line — the coastline of the Oceanus Germanicus — lay approximately 120 km further south during antiquity than today; (ii) real geodynamic processes (CDF reactivation, lateral extrusion, multi-layer décollement glide,

rigid block rotation, and now the unified-Abnobae sinistral rotation) constitute a secondary, quantitatively investigated component requiring multi-layer kinematic treatment. The model is falsifiable through a battery of 34 explicit tests (T1–T34).

Projektwebsite: https://www.ancientmaps-geography.com

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A New Interpretation of Ptolemy's Germania Magna: Employing Computer-Assisted Image Distortion of a Medieval Map by Donnus Nicolaus Germanus to Examine Post-Glacial Geodynamics in Europe

based on Mildner, S. (2026). A New Interpretation of Ptolemy’s Germania Magna: Cartometric, Geodynamic, and Historical Evidence for a Long-Term Transgression and Post-Antique Regression of the Oceanus Germanicus in Central Europe (Version 5). EarthArXiv (Preprint). https://doi.org/10.31223/X5313T

This paper revises and extends the author’s earlier interpretation of Claudius Ptolemy’s Germania Magna (c. 150 AD) by combining a cartometric analysis of the medieval
map redaction of Donnus Nicolaus Germanus with evidence drawn from geodynamics, palaeohydrology, palynology, archaeology, and historical chronology. Its central thesis is that the apparent discrepancies between Ptolemy’s coordinate system and the modern Central European landscape are not primarily the result of ancient measurement error, as the prevailing geodetic-rectification school has assumed, but the cumulative product of two superimposed factors: a substantial, geologically recent transformation of the landscape itself, and the inevitable cartographic distortion that arose when medieval and early-modern editors re-projected Ptolemy’s coordinates onto an already changed terrain without recognising the underlying shift. The most consequential change concerned the coastline of the Oceanus Germanicus. During antiquity, this coastline ran approximately 120 km south of its present position, just north of present-day Berlin, at the latitude of Eberswalde. North of this line stretched not open sea in the modern sense, but a wide amphibious zone of marshes, reed flats, shallow lagoons and reticulated waterways — a landscape that on approach from the sea offered no clear shoreline at all. Within this framework, the Vistula Fluvius of Ptolemy corresponds not to the modern Polish Vistula but to the Lusatian river system of the Schwarze Elster, Spree and Oder; the Asciburgius Mons corresponds not to the Sudetes but to the Fläming and its south-eastern foothills; and the southern boundary river that Ptolemy calls Danubius may, on a revised reading, correspond to the modern Main rather than to today’s Danube, with the Abnoba Mons of his text identified with the Taunus rather than the Black Forest. The hypothesis advanced here is that the relevant landscape transformation occurred in geologically recent time — most plausibly during a window centred on the midsixth century AD — and was driven by a late-stage reactivation of the Caledonian Deformation Front (CDF) and adjacent structures of the Trans-European Suture Zone under the compressional regime of the closing Alpine orogeny, with the possibility of an impact or airburst trigger of cometary origin that may have catalysed the deformation. The proposed framework offers a unified explanation for the archaeological settlement hiatus of the fifth to seventh centuries, the abrupt collapse of arboreal pollen curves in the same window, the Late Antique Little Ice Age now widely recognised in tree-ring records (Büntgen et al., 2016), the political collapse of the Thuringian kingdom in 531 AD, and the subsequent Slavic re-colonisation of an emptied and ecologically reset landscape.

Projektwebsite: https://www.germania-magna.de,

based on the earlyer German PREPRINT title Mildner, Sven. (2020). Die Neuinterpretation der Germania Magna des Claudius Ptolemaios durch Sven Mildner - mit Hilfe computergestützter Bildverzerrung einer mittelalterlichen Kartendarstellung des Donnus Nicolaus Germanus - und Betrachtungen zur postglazialen Geodynamik Europas, 10.23689/fidgeo-5907. (engl. The Reinterpretation of Claudius Ptolemy's Germania Magna - with the aid of computer-assisted image distortion of a medieval map by Donnus Nicolaus Germanus - and considerations on the postglacial geodynamics of Europe)