Rock Layers at River Level in the North Canyon (Grand Canyon Context)

Assuming "North Canyon" refers to a section of the **Grand Canyon** (often North Rim area or specific tributary), the rock units exposed at river level (Colorado River) from youngest to oldest are typically:

1. Mancos Shale (Cretaceous) — *if present; often eroded away in main canyon, more common in nearby regions.*
2. Dakota Formation (Cretaceous) — Sandstone/conglomerate; often caprock.
3. Morrison Formation (Jurassic) — Colorful mudstones, dinosaur fossils.
4. Salt Wash Member (Morrison) — Sandstone lenses, uranium mining history.
5. Bluff Sandstone (Jurassic) — Eolian cross-bedded sandstone.

Important Context

• **Grand Canyon's river-level rocks are MUCH OLDER** (Vishnu Basement Rocks ~1.7 Ga, Grand Canyon Supergroup ~1.2–0.7 Ga, Tapeats Sandstone ~508 Ma). The list above represents **younger Mesozoic layers** found on the **rims or plateaus** (Kaibab Plateau, etc.), **not at river level in the inner gorge**.
• If "North Canyon" refers to a specific side canyon (e.g., Nankoweap, Kwagunt), the stratigraphy varies.
• These units are prominent in the **Grand Staircase** (Vermilion/White Cliffs) north of Grand Canyon.

For accurate identification, a specific location (river mile, side canyon) is essential.