What are stromatolites?
We see some stromatolites, followed by research scientist Rob Rainbird sitting on a boulder on the shores of the Ottawa River.
“Stromatolites are organosedimentary structures that formed on the shallow seafloor, and they’ve been known to occur back in Earth history as far as 3.5 billion years.”
Shots of algal mats, followed by sediments being tossed around in water.
“And so, they are structures formed by algal mats or microbial mats that were on the sea floor, and they contained cilia or filaments that are kind of sticky, and they grew up through the sediment, and they bound and trapped sediment that was in the water that was in the area.”
We go back to Rob sitting on the boulder and then zoom in on the layered rock he is holding.
“So those cilia sort of grew through and kept on growing up and trapping more and more sediment, and it got built up in a series of layers like you see here.”
Shots of sediments being tossed around in water.
“So each layer is a layer of sediment that was trapped, and not only would sediment be trapped there, but you had precipitation of calcium carbonate or limestone in between those layers.”
Back to Rob holding the layered rock.
“We had a combination of chemical precipitation going on and physical sedimentation going on. And as time went on, these layers just built up and up and up — and so, leaving behind the structures that we see in this rock.”
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Can Rocks Preserve Clues to Ancient Life?
Text on screen: Stromatolites are layered rock structures formed by communities of microorganisms.
Research scientist Rob Rainbird is kneeling down on an outcrop of stromatolites next to Carleton University professor Allyson Brady and her student Kyla Malo. Allyson addresses Rob
“One thing she can tell you about is her research project is actually trying to understand if there are organics that are preserved in these stromatolites. So that’s what she’s been investigating with these samples.”
We focus on Kyla, who then points at the layers of a stromatolite formation.
“Yeah, because of the way that stromatolites are formed with the micro-organisms, sometimes the organics that the organisms produce can become trapped and preserved over time scales. So this exposure here is perfect to look at how these biomarkers are preserved over these geologic time scales.”
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