Geological Map of Crete

Project Overview

The Hellenic Survey of Geology & Mineral Exploration (HSGME) commissioned me the design of a unified Geological Map of Crete, a task as much scientific as was aesthetic. Crete’s terrain embodies the drama of the Mediterranean—tectonic complexity, contrasting lithologies, and centuries of research layered into a dense geospatial history. The goal was to consolidate decades of geological data held by the national agency into a single, coherent visualization that would serve both as a functional scientific reference and as a showcase of cartographic precision.

The project began with a massive database of vector and raster datasets, each representing geological formations, faults, stratigraphic units, and topographic contours. The data came in various projections and formatting standards, reflecting the island’s long mapping history. My mission was to unify all these elements under one consistent visual language and to deliver a map that respected both the geological integrity of the source material and the design standards expected from a modern national-level cartographic product.

Picture 1, represents the core outcome of that process: a complete view of the island rendered in refined color schemes and stratigraphic logic. It introduces the project in its most comprehensive form, a synthesis of scientific precision and visual harmony. The map communicates Crete’s structural fabric with clarity: the tectonized units of the Hellenides, the sedimentary layers of the Neogene basins, the metamorphic complexes of the interior mountains, and the recent Quaternary deposits along the coasts.

This image serves as the visual anchor of the project narrative. It presents the final outcome before the story rewinds to unpack how each layer, color, and symbol came together through months of methodical cartographic work.

Challenges

The first challenge was conceptual: how to represent Crete’s geological diversity within a limited color space while maintaining legibility across dozens of overlapping lithostratigraphic units. HSGME’s datasets included extensive classifications, each with their own symbology conventions developed across different time periods and regional teams. My task was to merge these conventions into a single consistent schema without diluting scientific meaning.

A second challenge was purely technical. The raw geospatial data arrived in multiple coordinate systems, many of them legacy projections dating back to early national surveys. Merging these datasets required careful re-projection, topology correction, and generalization without losing key structural features like fault alignments and unit boundaries.

Picture 2 illustrates these early stages. It is a close-up view that exposes the complexity of the geological data, dense, colorful, but chaotic. Each color block, line, and label represents not only a lithological unit but also the interpretative decisions of past geologists. This visualization encapsulates the problem to be solved: to bring coherence and elegance to a dataset too intricate for direct visual consumption.

Crete’s scale and detail imposed its own limitations. The map had to function both as a broad educational tool and as a technical reference, readable at multiple scales. Maintaining that duality required careful management of symbol hierarchy and annotation density. Geological maps are inherently verbose; too many colors or labels can quickly overwhelm the viewer. My role was to strike the delicate balance between scientific completeness and cartographic restraint.

Design Process & Design Decisions

The design process began with a close examination of HSGME’s database structure. Each unit was cross-referenced against the international geological time scale to establish color consistency with global standards. I referenced the International Chronostratigraphic Chart published by the International Commission on Stratigraphy as shown in Picture 3.

This chart became the color and classification backbone of the entire project. It defines not only the temporal divisions of Earth’s history but also the internationally accepted chromatic palette for each era, from the pale blues of the Quaternary to the deep reds of the Precambrian.

Picture 4 shows the extracted color palette derived from that chart. I imported these standardized hues into ArcGIS Pro, ensuring that each stratigraphic unit in Crete corresponded to its chronostratigraphic equivalent on a global scale. The challenge was to adapt these pure colors into a harmonious whole suitable for screen and print, accounting for perceptual uniformity and contrast. The palette underwent several iterative refinements until it could maintain differentiation among closely related formations without visual noise.

With the color system defined, attention shifted to the spatial organization of the data. Picture 5 documents one of the intermediate stages in ArcGIS Pro, where the geological units, faults, and structural features were layered, classified, and symbolized. Each polygon represented a formation with coded attributes referencing lithology, stratigraphy, and age. Faults were stylized as subtle, tapering lines to emphasize geological structure without overwhelming the surface colors.

Throughout this process, I continuously evaluated the map for readability and balance. The legend was treated as a narrative device rather than a static index. It guided the reader through Crete’s geological story: from the ancient metamorphic cores of the island to the younger sediments deposited in its coastal basins. Each legend entry was carefully aligned with its cartographic representation, forming a cohesive visual system.

As the GIS base evolved, I began to consider the map’s compositional balance. The coastline of Crete forms a natural frame, but its long, irregular shape presents challenges for layout. The island’s length far exceeds its width, so the final composition had to use space efficiently while keeping textual annotations readable. This stage involved countless adjustments to placement and scale, where typographic elements were first integrated.

Typography in geological maps carries scientific weight. I selected a legible sans-serif for modern clarity and paired it with a restrained serif for unit labels, maintaining hierarchy without ornamentation. Label density was controlled through scale-dependent visibility in ArcGIS, ensuring that at broader scales only major formations and tectonic structures appeared.

I developed custom geological symbols to depict bedding, fault orientation, and structural directions. Using Adobe Illustrator, I redrew these symbols by hand, guided by international geological cartography standards. The aim was to harmonize traditional geological conventions with the project’s clean, digital aesthetic. Each symbol had to communicate effectively at small scales while remaining faithful to its geological meaning (Picture 6).

Integration between GIS and Illustrator formed the bridge between data accuracy and visual polish. I exported high-resolution vector layers from Illustrator and imported them into ArcGIS Pro, where final adjustments to color, stroke weight, and annotation placement were made. This dual-environment workflow allowed me to maintain scientific precision while achieving the design finesse expected in published maps.

This design chapter represents the most substantial phase of the project—not only in time spent but in the creative synthesis it demanded. The work required navigating between the technical rigor of geology and the artistic discipline of design. Every color, symbol, and label reflected both scientific reference and human interpretation.

To enhance the geological information with topographic and geomorphological context, I incorporated a terrain base derived from the NASADEM digital elevation model. This global elevation dataset provided a precise, high-resolution foundation for representing Crete’s dramatic relief, from its rugged interior mountains to its deeply incised valleys and coastal plains. The raw elevation data were imported into ArcGIS Pro, where I processed and refined them through hillshading, contour extraction, and vertical exaggeration adjustments to highlight the island’s physiography without distracting from the overlying geological layers.

The shaded relief was carefully calibrated to complement the color palette of the geological map, ensuring that the subtle variations in light and shadow would enhance, rather than compete with, the stratigraphic colors. Contours were rendered in muted tones to give a sense of depth and topographic realism. This integration of terrain provided the essential geomorphological framework that tied the geological formations to their physical landscape, revealing how tectonic forces, erosion, and sedimentation shaped the island’s current form.

As the design process advanced, the project extended beyond the 1:50,000 dataset into a broader-scale synthesis at 1:200,000. This transition was not a simple rescaling but a conceptual shift. The large-scale dataset captured the intricate local details of Crete’s geology, like fault traces, unit boundaries, and lithological nuances, while the smaller-scale map aimed to communicate the island’s overall geological structure.

Picture 9 represents this stage: the geological map of Crete at 1:200,000 scale. At this level of generalization, clarity depended on distillation. Individual formations were grouped into broader lithostratigraphic categories, and secondary faults were omitted to preserve the visual rhythm of the map. In creating this smaller-scale version, I faced the challenge of simplifying without erasing meaning. The reduction of detail required new symbology rules, such as simpler linework, broader color fields, and strategic label placement. The resulting map achieved a delicate balance between scientific rigor and legibility, transforming the dense geological data into an elegant overview suitable for publication and display.

A variation of the same dataset, shown in Picture 9, reinterprets the geological base as a hydrogeological visualization. Here, the rendering emphasizes aquifer distribution, permeability zones, and lithological water-bearing characteristics. Rather than focusing on stratigraphic time, the color palette was adjusted to reflect hydrogeological function, ranging from permeable limestones to impermeable shales. This map provided an alternate lens through which to understand Crete’s subsurface dynamics, supporting hydrological studies and water-resource management initiatives.

The close-ups shown in Picture 10 capture the refinement of both renderings at a more intimate scale. These detailed sections illustrate how the generalization process maintained spatial clarity while preserving the essential narrative of the island’s structure. Even when viewed at magnified resolution, the maps retain their compositional harmony—proving that thoughtful design and consistent symbology can bridge scales without losing coherence.

This final stage of design symbolized the completion of a full cartographic arc: from the intricate precision of the 1:50,000 geological dataset to the broad synthesis of the 1:200,000 island-wide visualization, and finally, to the derivative hydrogeological map that reimagined the same terrain through a new interpretive framework.

Solution & Outcome

The final map represented a synthesis of data precision and visual coherence. The process of unifying datasets, refining colors, and balancing symbology culminated in a product that could serve scientific, educational, and institutional needs simultaneously. The Geological Map of Crete achieved what had initially seemed contradictory: maintaining the granularity required by researchers while presenting an aesthetic clarity accessible to a broader audience.

Solving the original problems, like heterogeneous data, inconsistent projections, and outdated symbol conventions, required an iterative and hybrid approach. Every stage of work built upon the previous one with measured discipline: from raw geological layers to the refined and composited design that now serves as a national reference. Each unit, line, and annotation was validated against the original HSGME dataset to ensure that no geological interpretation was altered in translation.

Innovation emerged not through radical reinvention but through subtle integration. The most powerful improvements came from harmonizing standards, like the international chronostratigraphic palette, modern GIS cartography, and the design sensitivity of contemporary mapmaking. The fault network, once visually chaotic, became a quietly expressive structural rhythm guiding the reader’s eye across the island. The color hierarchy, once uneven, now told a story of time and transformation, from ancient metamorphic substrates to young alluvial plains.

Equally important was the consideration of user experience. Geological maps are complex documents, often intimidating to non-specialists. My objective was to make this map not only scientifically sound but also inviting. Careful spacing, consistent legend structure, and visual breathing room turned the dense geological record of Crete into a narrative landscape, readable at a glance, but rewarding deeper inspection.

When printed at exhibition scale, the map held its detail; when displayed digitally, its composition remained balanced. This scalability was a critical success measure. The final map could be used in printed atlases, research posters, educational presentations, or high-resolution interactive formats without losing integrity.

Value & Impact

The completed Geological Map of Crete provided HSGME with a tool that went beyond internal documentation. It became a communicative instrument capable of representing the agency’s scientific authority while also demonstrating modern cartographic craftsmanship.

For the client, the project delivered immediate value by transforming an extensive geological database into a clear, standardized, and publishable visualization. The map unified disparate regional datasets under one visual identity, aligning national cartographic practice with international geological standards. It also established a workflow model for future HSGME projects, demonstrating how legacy data could be reimagined and brought to life through contemporary design tools.

For the audience, the impact was both intellectual and aesthetic. Researchers gained a consolidated view of Crete’s structural and stratigraphic organization, while students and the public could appreciate the island’s geological richness through color and form. The map conveyed not only scientific information but also the beauty inherent in Earth’s geological order. It celebrated the complexity of Crete’s landscape without overwhelming the viewer.

The project also highlighted the power of collaboration between scientific institutions and designers. The partnership with HSGME underscored how cartography operates as a bridge discipline, one that translates technical data into human understanding. In this sense, the project’s success was measured not just by the map itself, but by the clarity and accessibility it brought to the science it represents.

Reflection

Looking back on the process, what stands out most is the relationship between structure and intuition. Geological data is rigorous and coded, but translating it into visual form requires interpretive sensitivity. Each step demanded judgment: where to simplify, how to emphasize, what to let recede. The work deepened my understanding of how scientific maps function as both documents and artworks and records of data and reflections of perception.

From a professional standpoint, the project strengthened several essential skills. It honed my ability to manage complex datasets across multiple platforms, maintaining geospatial accuracy through each transformation. It reinforced precision in symbology design, developing vector-based systems that remain legible and expressive across scales. It also refined my capacity to tell visual stories: to use hierarchy, color, and spatial rhythm to guide the reader’s experience of a map.

If I were to approach a similar project again, I would explore expanding the output into an interactive format, where users could toggle between layers, ages, or formation types. While this version was designed for static presentation, the data architecture would lend itself well to web-based visualization. Interactive geological maps can engage a broader audience, bringing the underlying science closer to the public imagination.

Ultimately, the Geological Map of Crete reaffirmed why I pursue cartography: it is the art of revealing patterns hidden in data. Each contour line, each color transition, represents a fragment of Earth’s history, reassembled through human observation and design discipline. Seeing those histories align visually and conceptually remains one of the most rewarding experiences of this field.

Credits / Collaboration

This project was realized through the collaboration and data resources provided by the Hellenic Survey of Geology & Mineral Exploration (HSGME). Their trust and openness in granting access to their geological database made it possible to design a comprehensive and accurate visualization of Crete’s geological structure.

Technical and methodological insights from HSGME geologists were invaluable in cross-checking unit classifications and verifying structural interpretations. Their expertise ensured that the final design did not simply visualize geology but accurately conveyed it.

A special acknowledgment is extended to Ioannis Michalakis, from HSGME, who first conceived the initiative and commissioned the project. His guidance and supervision were instrumental throughout the process. From the early conceptual stages to the final verification of data integrity, his insight ensured that the design remained faithful to geological accuracy while advancing the agency’s cartographic standards. His commitment to innovation and clarity in national geological mapping provided both direction and inspiration during every phase of the work.