5.1 Seafloor Features
The ocean floor is not flat but features dramatic topography: mid-ocean ridges, deep trenches, volcanic seamounts, and vast abyssal plains. These features tell the story of plate tectonics.
Major Seafloor Features
Mid-Ocean Ridges
65,000 km underwater mountain chain. New crust forms here. Avg depth 2500m.
Ocean Trenches
Deepest ocean features. Mariana Trench: 10,994m. Subduction zones.
Abyssal Plains
Flattest places on Earth. 4000-6000m deep. Covered by fine sediments.
Seamounts
Underwater volcanoes. >100,000 in Pacific alone. Hotspots for biodiversity.
Continental Margins
Shelf
0-200m. Shallow, sunlit. 8% of ocean but rich fisheries.
Slope
200-2000m. Steep gradient. Submarine canyons.
Rise
2000-4000m. Gentle slope. Sediment fans.
Hypsometric Curve
Earth's elevation distribution shows two peaks: continents (~0-1000m) and ocean floor (~4000-5000m)
3,688 m
Mean ocean depth
10,994 m
Maximum (Challenger Deep)
Python: Ocean Depth Profile
#!/usr/bin/env python3
"""seafloor_features.py - Ocean depth statistics"""
import numpy as np
import matplotlib.pyplot as plt
# Simplified hypsometric curve data
elevations = np.array([-11000, -6000, -4000, -2000, -200, 0, 200, 1000, 8848])
cumulative_area = np.array([0, 1, 30, 78, 92, 100, 71, 21, 0]) # % of Earth's surface
plt.figure(figsize=(10, 6))
plt.fill_betweenx(elevations, 0, cumulative_area, alpha=0.3, color='blue')
plt.plot(cumulative_area, elevations, 'b-', lw=2)
plt.axhline(0, color='cyan', linestyle='--', label='Sea level')
plt.axhline(-3688, color='navy', linestyle=':', label='Mean ocean depth')
plt.xlabel('Cumulative Area (%)')
plt.ylabel('Elevation (m)')
plt.title('Hypsometric Curve')
plt.legend()
plt.grid(True, alpha=0.3)
# Ocean depth statistics
depths = {
'Pacific': 4280,
'Atlantic': 3646,
'Indian': 3741,
'Southern': 3270,
'Arctic': 1205
}
print("Mean depths by ocean:")
for ocean, depth in depths.items():
print(f" {ocean}: {depth} m")