Which statement about strike direction in the United States is true?

• A. Not standardized
• B. Not applicable
• C. False
• D. NE or NW

Answer: (D)

Strike direction is the compass bearing of the line formed by a rock bed where it intersects a horizontal plane. It’s measured on a map and reported as a direction like NE or NW, and it runs along the bed, perpendicular to the dip direction. In the United States, the broad structural patterns and tectonic history tend to align features along northeast or northwest trends, so the lines that represent bed and fault strikes are commonly NE–SW or NW–SE in many regions, making NE or NW a typical, accurate descriptor. The other options don’t reflect how strike is expressed or the regional orientation you’d expect on US maps.