It's as if everything was flipped upside down. He believes, and there is considerable proof to back him up, what are now the ridges used to be the rivers, and the modern day rivers used to be the ridges. He lays out his theory really in the first few pages so you don't need to read the whole thing, although it is one of the better papers on placer mining in California. I went back and re-read Lindgren's paper. The theory makes an awful lot of since when you start looking at where the tertiary channel ran. As simple as it sounds it forces you to think differently. "Simple theory," my friend replied, "What's up used to be down, an what's down used to be up."Īnd there it is in a nutshell. Like most prospectors of the Sierras I had read Waldemar Lingren's paper "The Tertiary Gravels of the Sierra Nevada" published in 1911, but I didn't recall any theory of inverse topography. We didn't find the tunnel that day, but as we were walking the side of the hill my friend mentioned how the country we were in was a perfect example of Lindgren's Theory of Inverse Topography. This area wasn't well known for drift or hydraulic mines but based on the bearing the drift was running it looked like it was tunneling into a ridge which further south had a tertiary channel beneath it. We spent some time hiking the area wondering why a drift tunnel would be where I found it. The year before I had found this tunnel, then lost it again but I knew about where it was. We decided we were going to go find an old drift tunnel which was still open. It's not often you have this chance so I looked forward to learning from someone who had a lot more knowledge than I did. There's always a reason.Ī few weeks ago I had the opportunity to go prospecting with a professional geologist. We hear the tertiary channel crossed right there, or there was a big vein that bled into the creek and huge nuggets have been pulled from there. Not surprisingly we convince ourselves the next canyon has better gold because there is a reason for it. No matter how good our current claim is, we're always willing to give up on it and head over the next ridge where there's supposed to be even better gold. Each trip is another opportunity to learn something. Prospecting is an endless process of learning.
Today, we know the source was the ancient tertiary river channels, but still we often ask how these channels managed to be at the top of the Sierras, not the bottom like present day rivers. The source of the placer deposits in the Motherlode was of great interest to early prospectors and geologists. Today, what we take for common knowledge on prospecting, wasn't always so. The Sierra Buttes stand as proof of Lindgren's Theory
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