By the time these ammonites were being buried in sediment, Wrangellia, the predominately volcanic terrane that now forms Vancouver Island and the Queen Charlotte Islands, had made its way to the northern mid-latitudes.
Within the basal part of the sequence, sedimentary beds are found interbedded with lapilli and crystal-tuffs. Here you'll see maroon tuffaceous sandstone, orange-grey sandstone, granule sandstone and conglomerate. Within them we find ammonites nestled in with gastropods and pelecypods.
While the fossiliferous outcrop is quite small, the Bonanza group is much larger, estimated to be at least 1000 metres thick. The site is quite small and in an active logging area, so the window to collect was limited. The drive up the mountain was thrilling as there had just been heavy rains and the road was washed out and narrowed until it was barely the width of our wheelbase and then narrowed further to be just shy of the width of the vehicle — thrilling, to say the least. So scary that my passengers all got out as there was a high probability of going head-first over the edge. I navigating by some handwritten field notes and a wee map on a paper napkin that should have read, "park at the bottom and hike up." Nope. We didn't park at the bottom and were halfway up the mountain before the road narrowed out. Too narrow to turn around, so the only way was up.
|Coroniceras with a sweet, sweet keel|
She and I had just done a trip up to Goldbridge where the cliff we were on had turned into a landslide into a ravine so she was feeling understandably cautious about the power of Mother Nature. Picture the angle, the hood of my jeep riding high and hiding what remained of the road beneath and a lovely stick shift that made you roll backwards a wee bit with every move to put it into gear. So, without being able to see the very narrow path beneath, I had to just keep going. Both Perry and Patricia helped with filling in the potholes so my tires would have something to grip. I bent the frame on the jeep heading up and had some explaining to do when I returned it to the car rental place.
In the end, we found what we were looking for. Memekay yields a mix of ammonites, gastropods and bivalves. Many of them poorly preserved. It was a hell of a ride but well worth the effort as we found some great fossils and with them more information on the palaeontology and geology of Vancouver Island. Just look at the keel on this beauty.