DR. J. W. DAWSON ON ERECT TREES CONTAINING ANIMAL 
material. Others remained open till the deposition of the overlying sandstone, and 
must have been still about 9 feet high, when finally filled. These are the most 
productive of animal remains. The normal character of the deposits in such taller 
trees is represented in fig. 1. At the base is a layer of mineral charcoal representing 
F%. 1. 
Section of erect tree. 
( a ) Coal. (&) Coaly shale. (c) Gray shale. (cZ) Sandstone. (e) Land surface. 
(cZ) Argillaceous sandstone. (/) Mineral charcoal. (g) Carbonaceous deposit, with animal remains. 
(Ji) Sandstone, filling interior of trunk. 
the debris of the trunk itself, and sometimes containing a sandstone cast of the pith. 
Above this is a variable quantity of more or less indurated sandy matter, in layers, 
which, owing to pressure, are often concave above. This is blackened with organic 
matter, and contains fragments of bark and comminuted plants, with occasional leaves 
of Corclciites or fragments of stems of Ccdamites. It contains the greater part of the 
animal remains, though a few of these occur in the sandstone above. This deposit, 
which is the productive layer of the several trees, evidently consists of matter which 
fell into the hollow trunks or was washed in by rains, while the trees were still open 
at the surface of the soil. Above this productive layer are layers or sometimes a 
continuous deposit of sand, by which the trees were finally filled, and which contains 
no organic remains except fragments of drifted plants. Thus the productive portion 
of each tree is found near its base. After the final filling and the deposition of 
additional sediment, the greater compressibility of the matter contained in the trees 
