sedimentary
André's Landing Rock (Sandstone Boulder)
Newark Supergroup Sandstone (likely Stockton Formation)
AI-generated identification · may be incorrectHardness: 6-7 (Mohs); Color: Gray to tan with green moss/lichen; Luster: Dull/Earthy; Crystal Structure: Granular/Clastic; Cleavage: None; Specific Gravity: 2.2-2.8.
- Hardness
- 6-7 (Mohs)
- Color
- Gray to tan with green moss/lichen
- Luster
- Dull/Earthy
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Physical properties
Hardness: 6-7 (Mohs); Color: Gray to tan with green moss/lichen; Luster: Dull/Earthy; Crystal Structure: Granular/Clastic; Cleavage: None; Specific Gravity: 2.2-2.8.
Formation & geological history
Formed during the Late Triassic Period (approx. 200-220 million years ago) in a rift basin. It is a glacial erratic—a boulder transported by ice during the last glacial period and deposited as the ice melted.
Uses & applications
Historical monument and geological landmark. Commercially, such sandstones (brownstone) were widely used in 19th-century architecture and construction.
Geological facts
The rock marks the spot in Haverstraw, NY, where British Major John André landed to meet Benedict Arnold on September 21, 1780, to discuss the betrayal of West Point. It is a key artifact of American Revolutionary War history.
Field identification & locations
Identify in the field by its medium-to-coarse grain size, distinct bedding planes common in sedimentary rock, and the 'ANDRE LANDED HERE' inscription. Found along the Hudson River shoreline in Rockland County, NY.
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