feat(matplotlib): implement column-stratigraphic (#4905)

## Implementation: `column-stratigraphic` - matplotlib

Implements the **matplotlib** version of `column-stratigraphic`.

**File:** `plots/column-stratigraphic/implementations/matplotlib.py`

**Parent Issue:** #4573

---
:robot: *[impl-generate
workflow](https://github.com/MarkusNeusinger/pyplots/actions/runs/23121198649)*

---------

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Co-authored-by: github-actions[bot] <41898282+github-actions[bot]@users.noreply.github.com>

Author: github-actions[bot]

plots/column-stratigraphic/implementations/matplotlib.py

@@ -0,0 +1,201 @@
+""" pyplots.ai
+column-stratigraphic: Stratigraphic Column with Lithology Patterns
+Library: matplotlib 3.10.8 | Python 3.14.3
+Quality: 91/100 | Created: 2026-03-15
+"""
+
+import matplotlib.patches as mpatches
+import matplotlib.pyplot as plt
+import numpy as np
+
+
+# Data - synthetic sedimentary borehole section (depth increasing downward, younger at top)
+layers = [
+    {"top": 0, "bottom": 12, "lithology": "conglomerate", "formation": "Ogallala Fm", "age": "Miocene"},
+    {"top": 12, "bottom": 30, "lithology": "sandstone", "formation": "Arikaree Fm", "age": "Miocene"},
+    {"top": 30, "bottom": 50, "lithology": "siltstone", "formation": "White River Fm", "age": "Oligocene"},
+    {"top": 50, "bottom": 72, "lithology": "shale", "formation": "Chadron Fm", "age": "Eocene"},
+    {"top": 72, "bottom": 95, "lithology": "limestone", "formation": "Niobrara Fm", "age": "Cretaceous"},
+    {"top": 95, "bottom": 118, "lithology": "shale", "formation": "Carlile Shale", "age": "Cretaceous"},
+    {"top": 118, "bottom": 140, "lithology": "limestone", "formation": "Greenhorn Fm", "age": "Cretaceous"},
+    {"top": 140, "bottom": 158, "lithology": "sandstone", "formation": "Dakota Fm", "age": "Cretaceous"},
+    {"top": 158, "bottom": 175, "lithology": "siltstone", "formation": "Morrison Fm", "age": "Jurassic"},
+    {"top": 175, "bottom": 200, "lithology": "sandstone", "formation": "Entrada Fm", "age": "Jurassic"},
+]
+
+# Lithology styles: color, hatch pattern
+lithology_styles = {
+    "sandstone": {"color": "#F5DEB3", "hatch": "...", "edgecolor": "#8B7355"},
+    "shale": {"color": "#A9A9A9", "hatch": "---", "edgecolor": "#555555"},
+    "limestone": {"color": "#87CEEB", "hatch": "++", "edgecolor": "#4682B4"},
+    "siltstone": {"color": "#C4B69C", "hatch": "//", "edgecolor": "#8B7D6B"},
+    "conglomerate": {"color": "#DEB887", "hatch": "ooo", "edgecolor": "#8B6914"},
+}
+
+# Age group background colors for subtle shading
+age_colors = {
+    "Miocene": "#FFF8E7",
+    "Oligocene": "#F5F0E0",
+    "Eocene": "#EDE8D8",
+    "Cretaceous": "#E8EEF5",
+    "Jurassic": "#F0E8E0",
+}
+
+# Plot
+fig, ax = plt.subplots(figsize=(12, 16))
+
+column_left = 1.5
+column_width = 5.0
+max_depth = 200
+
+# Compute age spans
+age_spans = {}
+for layer in layers:
+    age = layer["age"]
+    if age not in age_spans:
+        age_spans[age] = {"top": layer["top"], "bottom": layer["bottom"]}
+    else:
+        age_spans[age]["top"] = min(age_spans[age]["top"], layer["top"])
+        age_spans[age]["bottom"] = max(age_spans[age]["bottom"], layer["bottom"])
+
+# Draw subtle age-group background shading
+for age, span in age_spans.items():
+    bg_rect = mpatches.FancyBboxPatch(
+        (column_left - 0.1, span["top"]),
+        column_width + 0.2,
+        span["bottom"] - span["top"],
+        boxstyle="square,pad=0",
+        facecolor=age_colors[age],
+        edgecolor="none",
+        zorder=0,
+    )
+    ax.add_patch(bg_rect)
+
+# Draw lithology layers
+for layer in layers:
+    top = layer["top"]
+    bottom = layer["bottom"]
+    thickness = bottom - top
+    style = lithology_styles[layer["lithology"]]
+
+    rect = mpatches.FancyBboxPatch(
+        (column_left, top),
+        column_width,
+        thickness,
+        boxstyle="square,pad=0",
+        facecolor=style["color"],
+        edgecolor=style["edgecolor"],
+        linewidth=1.5,
+        hatch=style["hatch"],
+        zorder=1,
+    )
+    ax.add_patch(rect)
+
+    mid_depth = (top + bottom) / 2
+    ax.text(
+        column_left + column_width + 0.4,
+        mid_depth,
+        layer["formation"],
+        fontsize=16,
+        va="center",
+        ha="left",
+        fontweight="semibold",
+        color="#2C2C2C",
+    )
+
+# Unconformity between Eocene (Chadron Fm, bottom=72) and Cretaceous (Niobrara Fm, top=72)
+unconformity_depth = 72
+x_wave = np.linspace(column_left, column_left + column_width, 80)
+y_wave = unconformity_depth + 0.8 * np.sin(x_wave * 4)
+ax.plot(x_wave, y_wave, color="#B22222", linewidth=2.5, zorder=3)
+ax.text(
+    column_left + column_width + 0.4,
+    unconformity_depth,
+    "unconformity",
+    fontsize=14,
+    va="center",
+    ha="left",
+    fontstyle="italic",
+    color="#B22222",
+    fontweight="medium",
+)
+
+# Age labels on the left with bracket lines
+bracket_x = column_left - 1.2
+for age, span in age_spans.items():
+    mid = (span["top"] + span["bottom"]) / 2
+    ax.text(
+        column_left - 1.8,
+        mid,
+        age,
+        fontsize=16,
+        va="center",
+        ha="center",
+        fontstyle="italic",
+        color="#333333",
+        fontweight="medium",
+        clip_on=False,
+    )
+    ax.plot(
+        [bracket_x, bracket_x + 0.4],
+        [span["top"] + 0.5, span["top"] + 0.5],
+        color="#555555",
+        linewidth=1.2,
+        clip_on=False,
+    )
+    ax.plot(
+        [bracket_x, bracket_x + 0.4],
+        [span["bottom"] - 0.5, span["bottom"] - 0.5],
+        color="#555555",
+        linewidth=1.2,
+        clip_on=False,
+    )
+    ax.plot(
+        [bracket_x + 0.2, bracket_x + 0.2],
+        [span["top"] + 0.5, span["bottom"] - 0.5],
+        color="#555555",
+        linewidth=1.2,
+        clip_on=False,
+    )
+
+# Legend
+legend_handles = []
+for lith, style in lithology_styles.items():
+    patch = mpatches.Patch(
+        facecolor=style["color"],
+        edgecolor=style["edgecolor"],
+        hatch=style["hatch"],
+        label=lith.capitalize(),
+        linewidth=1.0,
+    )
+    legend_handles.append(patch)
+
+ax.legend(
+    handles=legend_handles,
+    loc="upper center",
+    bbox_to_anchor=(0.55, -0.03),
+    fontsize=16,
+    framealpha=0.95,
+    edgecolor="#bbbbbb",
+    fancybox=True,
+    shadow=True,
+    title="Lithology",
+    title_fontsize=17,
+    borderpad=1.0,
+    ncol=5,
+)
+
+# Style
+ax.set_xlim(column_left - 2.8, column_left + column_width + 4.5)
+ax.set_ylim(max_depth, 0)
+ax.set_ylabel("Depth (m)", fontsize=20, labelpad=10)
+ax.set_title("column-stratigraphic · matplotlib · pyplots.ai", fontsize=24, fontweight="medium", pad=25)
+ax.tick_params(axis="y", labelsize=16, length=6)
+ax.set_xticks([])
+ax.spines["top"].set_visible(False)
+ax.spines["right"].set_visible(False)
+ax.spines["bottom"].set_visible(False)
+ax.yaxis.grid(True, alpha=0.12, linewidth=0.8, linestyle="--")
+
+plt.tight_layout()
+plt.savefig("plot.png", dpi=300, bbox_inches="tight")