This boulder is without a doubt the oldest item of historical
interest in Runcorn. It was deposited around 10,000 years ago.
The boulder is a glacial erratic. A piece of rock that deviates
from the size and type of rock native to the area in which it
rests; the name "erratic" is based on the errant location of these
boulders.
Geologists identify erratics by studying the rocks surrounding
the position of the erratic and the composition of the erratic
itself.
The bedrock of the western and north-eastern parts of runcorn is
comprised of rock from the Sherwood sandstone group; in the other
areas the bedrock is from the Mercia mudstone group. In places
there are prominent outcrops of sandstone, particularly at Runcorn
Hill and Halton Hill, which provide extensive views in all
directions. Elsewhere the bedrock is covered by drift. At the
north-west periphery of the town the drift consists of recent blown
sand, further to the east and bordering the Mersey it is recent
alluvium and elsewhere the drift consists of till.
The glacial irratic boulder is Ganite suggesting it came from as
far as the mountains of Scotland and northern England.
Erratics were once considered evidence of a massive flood
approximately 10,000 years ago, similar to the legendary floods
described in the texts of ancient civilizations throughout the
world.
In the 19th Century, many scientists came to favor erratics as
evidence for the end of the last glacial maximum (ice age) 10,000
years ago, rather than a flood. Geologists have suggested that
landslides or rockfalls initially dropped the rocks on top of
glacial ice. The glaciers continued to move, carrying the rocks
with it. When the ice melted, the erratics were left in their
present locations.
The boulder has been smoothed and rounded by the pressure and
movement of the glacial ice whilst in motion.
Other smaller glacial erratic stones can be found in Runcorn but
most of them have been moved from there original locations and set
into the ground to form fenders to protect old corner buildings,
walls and gate posts from damage from cart wheels.
In order to complete this cache you must estimate the horizontal
circumference of the boulder! Is doesn’t have to be accurate.
Also Take a photograph of yourself near to the boulder and post it
to the site.
Do you have any idea what kind of rock it is?
intrusive, felsic, or igneous?