KUJIvllY — SAXDPIPIOS IN MACNIOSIAN LIMIOSTONG OP DURHAM. 
297 
The pipes arc found in the limostono beneath the sand bods. 
I have never noticed them where the sand is absent ; and though 
they are sometimes filled with clay, or a mixture of clay and sand, 
yet in these instances a thin layer of sand is always the immediate 
cover of the limestone. Nevertheless, the quarrymen assert that 
pipes have occurred in other parts of the hill where the limestone is 
immediately covered by the boulder-clay. They do not occur 
towards the higher portion of the slope where the gravel is piled 
against the face of the limestone ; nor further up where the lime- 
stone is merely covered with turf; nor have they as yet been noticed 
in any other locality of the magncsian limestone. 
Ligii. 3. — Sand- and Clay-pipes on North Side of Quarry, the Alluvium removed. 
a a, Pipes filled wifh sand ; b h. Pipes filled witli clay ; g g. Thick-bedded, crystalline, and 
concretionary Umestone. Some of the pipes in this figui-e do not show their true 
terminations. 
The general foi'm of the majority of the pipes is tubular (figs. 
1 and 2), but often irregularly so ; some few are conical, but such are 
usually of slight depth ; others seem to be modifications of these 
forms ; occasionally they are almost flask-shaped (fig. 3), and in some 
instances, by the coalescence of two pipes, they appear to be bifid. 
The depth of the longest is about twelve feet, but in one case the 
termination was not reached at this depth. The depth of the 
majority is within six feet ; but there are pipes of all depths from 
one foot to twelve. 
Generally their width is proportionate to their depth, though in 
this they do not observe much uniformity. It is curious to observe the 
irregularity of width of some, especially of those I have termed flask- 
shaped. Such pipes arc of less width a foot or two below their 
apertures than towards each extremity, the lower portion of the 
tube being the most capacious. In some pipes I have nbticed a 
VOL. III. 2 p 
