Ray's Corner

Seek And Ye Shall Find

Ontario ’s Red Lake greenstone belt has an extensive sequence of stratiform marbles. Early geologists attributed their formation to subsurface hydrothermal emplacement, but by the early 70’s it was quite clear that they were of sedimentary origin, and were likely closely associated with underwater volcanic activity. In the mid ‘60’s I had seen similar formations in the Atikokan area, a characteristic of which had been the presence of deformed stromatolitic features (Precambrian life forms) up to perhaps a foot long and 6 inches across. No such features had ever been reported from the Red Lake area. Perhaps they didn’t exist, or perhaps no one had ever looked for them.

So, it became one of my objectives during our detailed mapping project to carefully examine the marbles at the west end of the lake in hopes of detecting stromatolites. The task was made somewhat easier by the fact that the marbles were generally readily accessible, and in fact they were often exposed along the shoreline. Their intimate relationship with interbedded cherts, argilliceous rocks, and occasional conglomerates sealed their fate once and for all as of sedimentary origin. But where were the stromatolites?

As I continued to seek evidence of the elusive ancient life forms, I began to see the occasional deformed structure in the marbles which, with some stretching of my imagination, I could unfold to give me a questionable stromatolite. “Not good enough,” I said to myself, “because if I’m having difficulty with these features, I’ll never convince anyone else of their validity. I’m trying simply trying too hard. And it’s likely these rocks have been too deformed to retain any traces of delicate stromatolitic features in any event!”

So I gave up the active search but couldn’t totally erase the notion from my mind. And then a week or so later at almost the last shoreline outcrop to be mapped, it happened! We had just nudged the boat up to an outcrop of marble when something at water level caught my eye as being too regular for this particular formation. We backed the boat off about five feet, splashed some water on the rock face for contrast, and there it was...a structure about three feet in diameter defined by narrow chert stringers arranged in a concentric pattern cut in turn by the odd chert stringer radiating from its center. The Geological Survey of Canada subsequently verified the structure as a stromatolite.

The outcrop had likely been examined by dozens of geologists over the previous 40 years, but their prime mission had been examining the quartz veins and rusty chert stringers for gold. The discovery of the stromatolites derived from the pursuit of a totally different objective, emphasizing the veracity of that old adage that we’d better know what we are looking for before we set out to find it.