been quarrying limestone in Northumberland County for over 60 years.
To most of us, that seems like a long time. However, compared to the
history of the limestone, 60 years is a mere fraction of an instant --
the limestone at the Meckley Quarry is 400 million years old, give or
take a few million years.
400 million years ago,
an inland sea lapped over what is now Northumberland County.
Geologists tell us that it was a shallow salt water sea, probably not
more than 40 feet deep.
climate was tropical because at that time, Pennsylvania was actually
located below the equator. (This is possible through "continental
drift". Over time, our state has slowly traveled to where it is
today, and it is still moving at the rate of a few inches per year).
Millions of tiny creatures lived in the warm tropical sea that covered
Pennsylvania. When they died, their shells broke into pieces and sank
to the sea floor. The shells chemically consisted of calcium and
As the bits and pieces
of shells accumulated over tens of millions of years, tiny crystals of
the mineral calcite grew into the spaces between the shell particles
and cemented them together. The calcite crystals are visible today as
the white streaks of mineral that you see exposed in pieces of rock
and along the highwall. After millions of years of heat and pressure,
these minerals formed the grey-colored solid-rock formation that is
currently being mined in the Meckley Quarry.