Calamites Stem Impression
Calamites cf. cisti • Body fossil (impression/compression) of a plant tissue
Geological Period
Carboniferous (Pennsylvanian sub-period)
Estimated Age
298 to 323 million years
Preservation Type
Carbonaceous impression/compression on a sedimentary plane
Condition Assessment
Fair; the specimen is a fragmentary impression with some loss of fine detail and significant weathering on the matrix edges
Taxonomic Classification
Phylum: Pteridophyta, Class: Equisetopsida, Order: Equisetales, Family: Calamitaceae, Genus: Calamites
Morphological Description
Features parallel vertical ribbing or striations characteristic of the outer surface of a horsetail-like giant tree. The ribs are separated by narrow grooves and show subtle nodal joints typical of the arborescent sphenopsids.
Rock Matrix
Ferruginous siltstone (red beds), likely an iron-rich mudstone or shale with characteristic oxidation
Formation & Location
Commonly found in the Pottsville Formation (USA), Mazon Creek (Illinois), or the Coal Measures of Europe (UK/Germany)
Size & Dimensions
Approximately 4-6 cm in width (fragmental); typical giant Calamites could reach heights of 30 meters
Value & Rarity
Estimated Market Value
$10.00 - $25.00 USD
Auction Estimate
$15.00 - $30.00 USD
Rarity Assessment
Common; Calamites fragments are ubiquitous in Carboniferous coal-bearing strata globally
Scientific Significance
Provides evidence of paleo-swamp ecosystems during the 'Coal Age,' demonstrating the dominance of giant spore-bearing trees in humid, tropical Carboniferous environments
Preparation Recommendations
No invasive mechanical preparation needed; clean with a soft dry brush and store in a stable, low-humidity environment to prevent further oxidation of the iron-rich matrix
Notable Features
The distinctive red coloration of the matrix indicates a high iron oxide content, likely formed in an oxidising terrestrial environment following deposition