spec: add column-stratigraphic specification (#4600)

## New Specification: `column-stratigraphic`

Related to #4573

---

### specification.md

# column-stratigraphic: Stratigraphic Column with Lithology Patterns

## Description

A vertical column visualization showing geological rock layers with
standardized lithology patterns, formation names, ages, and thickness
scales. Each layer is represented as a stacked rectangular block filled
with a distinctive pattern (e.g., brick pattern for limestone, dots for
sandstone, dashes for shale) following FGDC/USGS conventions. This plot
is essential for communicating subsurface geology and sedimentary
sequences in a compact, standardized format.

## Applications

- Stratigraphy: describing borehole or outcrop sections with
standardized lithology symbols for geological reports
- Petroleum geology: visualizing well log lithological intervals
alongside wireline log data
- Environmental geology: site characterization showing subsurface
material types and aquifer geometry
- Geological education: teaching sedimentary sequences, unconformities,
and stratigraphic principles

## Data

- `top` (numeric) - depth or elevation of the top of each layer in
meters
- `bottom` (numeric) - depth or elevation of the bottom of each layer in
meters
- `lithology` (categorical) - rock type for each layer (e.g., sandstone,
limestone, shale, siltstone, conglomerate)
- `formation` (string) - formation or member name for each layer
- `age` (string) - geological age label (e.g., "Cretaceous", "65 Ma")
- Size: 5-20 layers
- Example: a synthetic sedimentary section with 8-10 layers of varying
thickness and lithology, spanning multiple geological periods

## Notes

- Each lithology type should use a distinct fill pattern (hatching or
texture) that approximates standard geological map symbols (e.g., brick
pattern for limestone, stipple dots for sandstone, horizontal dashes for
shale, random dashes for siltstone)
- The vertical axis represents depth or thickness (increasing downward
by convention in borehole logs, or upward for outcrop sections); use
increasing downward for this spec
- Formation names should be labeled to the right of or within each layer
- Age labels or geological period names should appear on the left side
or as annotations
- A thickness/depth scale bar should be shown on the left axis with
appropriate units (meters)
- Layer boundaries should be drawn as solid horizontal lines;
unconformities may use wavy lines
- Use a minimum of 5 distinct lithology patterns to demonstrate variety

---

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---
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plots/column-stratigraphic/specification.md

@@ -0,0 +1,32 @@
+# column-stratigraphic: Stratigraphic Column with Lithology Patterns
+
+## Description
+
+A vertical column visualization showing geological rock layers with standardized lithology patterns, formation names, ages, and thickness scales. Each layer is represented as a stacked rectangular block filled with a distinctive pattern (e.g., brick pattern for limestone, dots for sandstone, dashes for shale) following FGDC/USGS conventions. This plot is essential for communicating subsurface geology and sedimentary sequences in a compact, standardized format.
+
+## Applications
+
+- Stratigraphy: describing borehole or outcrop sections with standardized lithology symbols for geological reports
+- Petroleum geology: visualizing well log lithological intervals alongside wireline log data
+- Environmental geology: site characterization showing subsurface material types and aquifer geometry
+- Geological education: teaching sedimentary sequences, unconformities, and stratigraphic principles
+
+## Data
+
+- `top` (numeric) - depth or elevation of the top of each layer in meters
+- `bottom` (numeric) - depth or elevation of the bottom of each layer in meters
+- `lithology` (categorical) - rock type for each layer (e.g., sandstone, limestone, shale, siltstone, conglomerate)
+- `formation` (string) - formation or member name for each layer
+- `age` (string) - geological age label (e.g., "Cretaceous", "65 Ma")
+- Size: 5-20 layers
+- Example: a synthetic sedimentary section with 8-10 layers of varying thickness and lithology, spanning multiple geological periods
+
+## Notes
+
+- Each lithology type should use a distinct fill pattern (hatching or texture) that approximates standard geological map symbols (e.g., brick pattern for limestone, stipple dots for sandstone, horizontal dashes for shale, random dashes for siltstone)
+- The vertical axis represents depth or thickness (increasing downward by convention in borehole logs, or upward for outcrop sections); use increasing downward for this spec
+- Formation names should be labeled to the right of or within each layer
+- Age labels or geological period names should appear on the left side or as annotations
+- A thickness/depth scale bar should be shown on the left axis with appropriate units (meters)
+- Layer boundaries should be drawn as solid horizontal lines; unconformities may use wavy lines
+- Use a minimum of 5 distinct lithology patterns to demonstrate variety

plots/column-stratigraphic/specification.yaml

@@ -0,0 +1,29 @@
+# Specification-level metadata for column-stratigraphic
+# Auto-synced to PostgreSQL on push to main
+
+spec_id: column-stratigraphic
+title: Stratigraphic Column with Lithology Patterns
+
+# Specification tracking
+created: "2026-03-06T19:53:29Z"
+updated: null
+issue: 4573
+suggested: MarkusNeusinger
+
+# Classification tags (applies to all library implementations)
+# See docs/reference/tagging-system.md for detailed guidelines
+tags:
+  plot_type:
+    - bar
+    - column
+  data_type:
+    - categorical
+    - numeric
+    - ordinal
+  domain:
+    - science
+    - geology
+  features:
+    - stacked
+    - annotated
+    - patterned