Sam is right, it is a very old buried river bed that has been exposed due to farming resulting in the underlying red shale being revealed. The whitish streaks are deposits caused by water percolating through the red iron oxide that depending on light can appear as faint blue or green.
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jmacd27, on Flickr
It is a fantastic site that unfortunately has been damaged by people not respecting the fragile shale. As I was leaving a family arrived and their three kids were running all over the site like it was a playground leaving visible marks of damage to the formations.
During my visit to photograph the site, workers were installing a fence around the site to prevent any further damage. The Bruce trail Association that manages the site will keep the site closed until they can come up with a plan that will allow access to the site with out causing further damage. This will probably take many years.
I am glad to have been to this site before being fenced off. It is a beautiful place and I spent quite a bit of my time there just sitting an enjoying the beauty of the sunrise light shifting on the rocks.
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jmacd27, on Flickr