
By William Gowland, F.S.A., FOI. 7 
No digging was carried on except in the presence of Mr. Blow, 
Mr. Stallybrass, or myself, and I made a point of being at the 
excavation before the work of each day began, and remaining until 
it was finished. 
A watchman was on duty at night to ensure that the excavations 
should not be tampered with. 
RocKS OF WHICH THE STONES CONSIST. 
Before proceeding to describe the excavations it may be well to 
consider briefly the chief kinds of rock of which the stones of 
Stonehenge consist, and of which chippings and fragments! were 
so numerous in the ground excavated. 
The large monoliths of the outer circle and the trilithons of the 
horseshoe are all sarsens. These sarsens in their composition are 
sandstones, consisting of quartz-sand, either fine or coarse, oc- 
_ casionally mixed with pebbles and angular bits of flint, all more 
or less firmly cemented together with silica. They are the relics 
of the concretionary masses which had become consolidated in the 
sandstone beds that once overlaid the chalk of the district, and had 
resisted the destructive agencies by‘which the softer parts of the 
beds were removed in geological times. They range in structure 
from a granular rock resembling loaf sugar in internal appearance 
to one of great compactness similar to and sometimes passing into 
quartzite. 
The monoliths and trilithons all consist of the granular rock. 
The examples of the compact quartzite variety, of which many 
were found in the excavations, were, almost without exception, 
_ either hammerstones that had been used in shaping and dressing 
_ the monoliths, or fragments which had been broken from off them 
in these operations. 
_ The small monoliths, the so-called “ bluestones,” which form the 
inner circle and the inner horseshoe, are, with the undermentioned 

1T am indebted to the kindness of my friend Professor Judd, Dean of the 
Royal College of Science, for the identification of the specimens of rock 
found in the excavations. The above is merely a rough summary of the more 
important kinds. For a complete account of them the reader is referred to 
_ Professor Judd’s note (post). 
