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Tours conducted of Federal Parliament’s oldest ‘member’


Parliament House is one of Canberra’s most renowned landmarks but it is far from its oldest. A 430 million-year-old rock formation dwelling in the basement provides a glimpse into Canberra’s ancient history.

Rather than living under one, the national parliament has been living on top of a 430 million-year-old rock for decades.

Located in Parliament House’s basement, the rock hides clues about some of the earliest life in Canberra. Referred to as the Capital Hill unconformity, the formation shows the connection of two rock masses that existed 10 million years apart.

A special tour of the formation took place earlier in March and is only conducted once a year.

Hosted by geologist and author Wolf Mayer, the tours provide a glimpse into the past as he explains what the rock formations mean and how its younger and older rocks can unpack Canberra’s ancient history.

“This is a useful and an extremely important remnant that is now housed in the basement of Parliament House,” Mayer told Region Media. “It is probably the only parliament house in the world with an unconformity in its basement.”

The rocks are made from sandstone, with mudstone scattered between, suggesting that Canberra was once at least two kilometres underwater.

“The unconformity that we see shows the tectonic plates moving and shifting, so it’s very important to us,” Mayer said.

“It is significant that it incorporates a piece of ancient history which has been preserved. Having parliament directly above it is a continuation of our current history, albeit there is a big gap in it all. It’s ancient history versus modern history, and they now sit one on top of the other.”

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