Size of Fossil Tree Stumps
Carboniferous lycopod trunks more than 100 feet long have been found in coal mines. These were buried laying on their sides. The preserved height of standing tree stumps is obviously much less, and is dependent on the space that was available for a tree stump to be buried before it had time to rot. In Kentucky, the heights of preserved fossil tree stumps are generally less than 6 feet. Easton (1913) reported an 8-foot-tall stump (including a photograph) from Harlan County. In underground coal mines, fossilized standing trees (called kettlebottoms) are often less than 4 feet tall, although taller stumps have been reported, and the height of a stump when seen from beneath cannot always be determined.
Measured diameters of stumps in outcrop are usually less than 3 feet across, although the stumps certainly widen at their base. In mines, where root bases are sometimes exposed, the stump bases more than 8 feet across have been reported.
Lyell (1842), in a letter to his sister, reported a standing fossil tree exposed in the cliffs at Joggins, Nova Scotia, that was 40 feet tall, although nothing close to that has ever been reported since. The 40-foot measurement may have been an estimation of the original height of the tree based on the size of the preserved stump, or a reference to a fossilized tree trunk laying on its side, rather than a preserved standing fossil stump. Most of the trees preserved at Joggins (which are still visible) are less than 6 feet tall. Brogniart (1821) illustrated a standing tree 10 to 13 feet high from a surface mine in France. Broadhurst and MaGraw (1959) likewise reported a 13-foot-high tree (which may have been as much as 38 feet long originally) from an opencast mine in England.
The preserved height of a fossil tree stump documents the available space for burial and preservation, called accommodation space by geologists. Although tall fossil tree stumps garner much attention, many small stumps are also preserved.