(Wikimedia Commons; Courtesy National Museum of Wales)
Stonehenge and its surrounding
area continue to offer new information
about how the prehistoric
site was used. A ground-penetrating
radar survey led by Vincent Gaffney
of the University of Birmingham has
revealed evidence of two large pits that,
when viewed from the Heel Stone, a
small standing stone near the entrance
to the site, align with sunrise and sunset
on the summer solstice. The pits may
have held wooden posts or standing
stones, and the area between them and
the Heel Stone may have been used for
summer solstice rituals.
Some of the stones from the site
were the subject of a different
study, by geologists Rob Ixer
of the University of Leicester and
Richard Bevins of National Museum
Wales, to determine where they came
from. The researchers used a technique
called "petrography," a common tool
for geologists for more than 100 years.
It involves looking at extremely thin
slices of rock under a microscope and
describing the way the minerals that
compose it blend with one another to
form a unique texture—as distinctive
as a fingerprint. By comparing rock
fragments from some of the site's
"bluestones" (a generic term used to
describe stones outside the site's iconic
center) to samples from a rhyolite
outcropping at Preseli Hills in West
Wales (above), Ixer and Bevins were
able to narrow down the area where at
least one stone had been quarried to a
six-by-15-foot space. The information
could lead archaeologists directly to the
places where Neolithic people cut the
rock that was made into Stonehenge
up to 5,000 years ago. The geologists
have examined about 700 pieces of
rock from Stonehenge but have only
completed analysis on a few pieces
of rhyolite. "I've been at this for 20
years," says Ixer, "but it is really just
the beginning."