A Dagger on Stone 30?

From:

A DAGGER IN RELIEF ON STONEHENGE?

R. E. Kaske

Traditio
Vol. 31, (1975), pp. 315-316
Published by: Fordham University
Article Stable URL:http://www.jstor.org/stable/27830990

... In May 1972, on a casual visit to Stonehenge, I noticed what appeared to be an incised cartwheel with eight spokes, low on the southeast side of stone 30, within the main entrance; this same apparent design was immediately recognized by my wife and son, with no prompting from me. When I re-examined the area in July 1974, I was astonished to find not oniy that I could see no cartwheel, but that I could see nothing which might plausibly have led me to think of a cartwheel. This striking discrepancy between two clear visual impressions of the same surface made me suspect that some delicate trick of lighting must be involved, and I accordingly visited Stonehenge at night to explore the problcm with the help of crosslighting. Instead of a cartwheel, there emerged the outline of what appears to be another dagger — generally similar to those found elsewhere on Stonehenge, but carved in relief and set within a rounded depression that I suppose may be partly man-made:

This dagger, like the others on Stonehenge., is approximately vertical with the point downward. It is about four inches tall and about one and three- quarters inches across at its widest part (the horizontal top of the blade). The surrounding depression has a horizontal diameter of about six and three-quarters inches, and presumably about the same vertical diameter; the rightmost point of its circumference is about eight inches from the outer edge of the stone (toward the road), while the presumed bottom point of its circumference is about sixteen. inches from the ground. On the blade of the dagger, the angle formed by the left vertical line and the horizontal top line has been chipped, apparently rather freshly. The handle is short, stumpy, and rectangular, like those on the other daggers of Stonehenge....

UPDATE : A photo taken by torchlight March 2013:

 Click for larger - Photo Peter Squire

UPDATED NOTE:
The area was thickly covered in lichen at the time of the Laser Scan and it is hard to make out but there is a shape in relief, standing out by about 4mm, in a rough circle. It doesn't seem to be a figment of the stoneworking but it is very unclear.
The spot is marked here.

(A previous note here referred to a different area)