Striation Mark
Definition
A scratch pattern made when a tool slides across a softer surface. Pry bar dragging across painted wood, blade cut, a screwdriver tip slipping in a strike plate.
- Formation
- Tool sliding across a softer surface
- Appearance
- Parallel or near-parallel scratches
- Common source
- Pry bar, blade, or slipping screwdriver
- Evidence category
- Tool mark evidence
Common questions
How does a striation mark differ from an impression mark?+
An impression mark forms when a tool is pressed straight into a surface, leaving a static negative shape. A striation mark instead forms from lateral motion, so it records the tool's edge as a series of parallel scratches rather than a single static outline.
How are striation marks compared to a suspect tool?+
Examiners make test marks with the suspect tool under similar conditions and compare the striation pattern under a comparison microscope, looking for a consistent sequence of matching ridges and valleys across the toolmark's width.
Related terms
- Class Characteristics
- Features deliberately or systematically imparted to a group of items by design or manufacture, such as the calibre of a bullet, the...
- Dynamic Mark
- A combination of compression and sliding in one contact. The most common real-world tool mark and the hardest to reproduce in test...
- Impression Mark
- A compression mark made when a tool meets a softer surface with no relative motion. Hammer face on brass, plier jaw crimping...
- Individual Characteristics
- Surface features on a fired bullet or cartridge case that arise from random or unique events (tool wear, corrosion, service damage) and...
- Test Mark
- A reference mark deliberately made with a suspect tool against a soft medium (lead, clay, aluminium) so it can be compared against...