Geological Maps

What are geological maps?

2D representations of 3D geologic features. Made on a topographic base map with contours and physiographic features

What are formation contacts?

Boundaries between formations

How are outcrop pattern of formations represented on a geologic map?

Shown with color and letter code for formation

What information is given on a Geologic Map Explanation?

Age, formation name and brief description of each formation. Formations listed in stratigraphic order so the relative ages are known.

How are formation contacts drawn on a geologic map?

Thin lines between formations

How are faults drawn on a geologic map?

Thicker lines represent faults

How are exposed faults drawn on a geologic map?

fault is solid line where exposed

How are inferred faults drawn on a geologic map?

fault is dashed where inferred

How are faults covered by younger sediment drawn on a geologic map?

fault is dotted line where covered by younger sediment

What is the Quaternary and how are Quaternary units labeled on a geologic map?

- 0-1.8 million years
- Deposits are labeled as 'Q' on a geologic map

What are Quaternary deposits?

- Qr - rockfall
- Qc - colluvium
- Qse - sheetwash and eolian

What is a Geological cross-section?

maps show only surface representation of geology. Cross-section (vertical slice through the earth) provides 3D understanding of geology