The alluvial fan with all the rounded boulders is now partly covered with the ragged remnants of a "second growth" forest. There are a few isolated older trees, but most of the larger remaining conifers are now only a bit over 100 years old. The old growth forest that preceded these trees was stripped and burned by early miners and homesteaders for various reasons. It must have been very smokey for a while back then, and from looking at old photos, not at all what we would currently call scenic. In a short period of time the slopes had been denuded.

People look at trees and decide whether they are picturesque, and usually do not think about how they came to look the way they do. It is hard now to imagine what the old growth forest on this alluvial fan would have been like. The vast area of the Province of British Columbia has very little old growth forest left uncut, and none in the local region with a similar aspect and elevation. The people who live on this fan appreciate the trees that still surround their homes, as long as they don't appear to create any danger - say, from falling down or burning up.

The old photos from the first few years of the twentieth century, showing vistas of denuded slopes sprinkled with burned, still-standing snags seem potentially seriously misleading. They might seem to imply that forests - and all they include - are miraculously resilient and can easily (if slowly) recover from any amount of devastation. Yes, most of those slopes are now covered in trees - wherever they haven't been removed by more recent wildfires and mechanised timber cutting operations. But back at the beginning of the twentieth century, the region was much more sparsely populated and the forest-devastating technologies available were much less efficient. And of course the climate crisis had not become apparent.

To the extent that humans interacted with nature differently back then, it was apparently due more to their limited technology than to their limited understanding. It still seems difficult to understand the extensive effects of the ways in which our current conceptualisation of nature is mediated by our technologies. And of course, so is our sense of our selves.

As I mentioned last week, when looking down into valleys from surrounding mountain peaks, I have sometimes attempted to visualise the protracted effects created by the shrinking glaciers at the end of the last ice age. One thing that prompted my efforts was actually a jumble of boulders down in a valley bottom. At the outflow of a relatively short, steep watershed there is a broad, convex alluvial fan that a creek flows across before entering a lake. At varying distances on either side of the present creek bed there are apparent former creek channels that are now dry and overgrown with vegetation.

When I first encountered this creek and the empty channels, I was impressed with all the large, rounded boulders strewn across the alluvial fan - some very large and moss covered, some encircled with tree roots and some in the current creek channel. That first encounter was over half a century ago, and those boulders on dry ground are still sitting there - except for a few that have been moved by people. In the last five decades there have been two significant debris-flow flood events in the creek, and those caused some of the smaller boulders in the creek channel to roll downstream, but none of the larger ones.

I eventually started wondering where those boulders had come from and how they could have become so smooth and rounded, and that got me thinking about the glaciers that filled all the valleys in the region during the last glaciation. It seemed to me that an immense amount of water, silt, sand, gravel, rolling rocks and time would be required to produce the millennia-old boulder piles on this alluvial fan. Considering the current benign hydrology in the area, it's hard to imagine how much cascading water must have been involved, eroding glacial moraines, tumbling and polishing large rocks. There's probably far more to the story - including higher former glacial lake levels - but those boulder piles at the bottom of the valley that are currently obscured by forest vegetation sparked my attempts to imagine a much broader picture. It does seem that change on time scales of many millennia require special effort to comprehend.

What sort of perspective can you gain from the top of a relatively "minor" mountain peak (one that no one would bother to brag about climbing)? Why would you want to climb such a "nondescript" mountain? Half Dome doesn't really fit in that category, but as I said last week, when I was sitting at the top of it so many years ago, I knew almost nothing about the complex biogeomorphological processes that shaped it and the rest of the world. So I didn't really know what I was looking at. I still don't know enough about those processes, but what I have learned has completely changed my perspective - and what I am now able to "see" from a "modest" summit.

Some of the higher peaks in the Pacific Northwest of North America have persistent snow fields, or even glaciers, on their north-facing upper reaches. While these have been continuously shrinking as the climate increasingly heats up, they can still provide reminders of the effects of the immensely thick layers of ice that blanketed this part of the Northern Hemisphere during the last ice ages. After all that grinding ice had carved out valleys and future lakes, the vast amounts of meltwater moved silt and gravel and boulders down all the slopes. Millennia of subsequent erosion further shaped the landscape.

North of the fiftieth parallel there are a series of mountain ranges between the Pacific Coast and the Rocky Mountains. When I have managed to scramble to the top of some peak, I have tried (however poorly) to visualise the changes that have occurred since the ice began to diminish ten or twelve thousand years ago. Whether my mental images of newly bare ground, fracturing ice, landslides, torrents of water and emerging lakes is at all accurate I will never know. I imagine that grasses and shrubs gradually covered the bare ground where the ice had been and then helped to form soils. I try to imagine the trees gradually progressing northward from their glacial refugia to the south beyond the maximum extent of the ice. I now know something about the subduction zones and terranes that formed the mountain ranges, and the isostatic rebound of the earth's crust after the weight of the ice sheets was removed, so that adds to the complexity. What I can "see" from the heights is the result of a number of very long processes.

The top of a peak can be a "viewpoint". From there, you can see some of what was not visible from somewhere down below. You could take some photographs to help remember the view, but what it means to you will depend on what you have learned - or might still learn - about the physical and biological processes spread out beyond that viewpoint.

"Overtourism", including in national parks where people can look at nature, has been in the news lately. For example, several accounts of crowding on the climb up Half Dome in Yosemite National Park in California have appeared in the media. During the high season, this crowding happens despite the permit system that reduces the daily number of people who have access to the climb to several hundred. In dry conditions, the coarse granite provides a fairly easy ascent for any reasonably fit person wearing appropriate footwear. There are fixed cables and some wood planks to increase safety on the steepest section. The top of the dome is very broad and relatively flat, providing enough room for lots of people to gather and look around.

I scrambled up Half Dome once by the cable route about 60 years ago, in the decade following the first ascent of its north face. Things were different then: many, many thousands of people have trooped up to the summit since. (Back then, that first north face ascent and the subsequent challenging north face routes were a big deal, in some circles.) On the pleasant, sunny fall day that I was there, only a handful of other people were around. From the top, the view was expansive - and perhaps enhanced by the fact that most of California's human artifacts had disappeared into the distant haze to the west. At least I was able to find some solitude in a secluded spot where I could better appreciate the many qualities of the location. (On the other hand, I didn't know much about geology, or glaciation - and nothing at all about plate tectonics - so most of what I could see was beyond me.)

For some people, one of the attractions of what we call "wilderness" is that they are better able in such surroundings to notice how they are alive - when they are removed from all the distractions of everyday life in their typical daily environment. It's obviously an important element in their development, and can be a source of much pleasure. While the top of Half Dome might appear to be quite solid and remote from human preoccupations, crowds of people scrambling around might detract from anything like a "wilderness experience". Of course, present day crowds don't seem to be looking for that sort of experience, and are more intent on consumptive viewing.

Present day Yosemite, or even the Sierra Nevada (and many other mountain regions), are obviously not the same kind of "wilderness" that Ansel Adams photographed, or that John Muir described...or anything like the place where the Ahwahnechee people once lived. Not only is every place much more crowded, but our concepts (and expectations) of "wilderness" and "Nature" have mostly changed. (This is not a veiled claim that there were ever any "good old days".) Before the internet and smart phones, far fewer people ever became aware of many places it has now become cool to be seen to have seen - but even back then there were already too many "visitors" to allow the continued existence of qualities that made the places special. That's not even accounting for the many costs of transporting all the visitors to all the destinations. Humanity's relationships with nature seem to be increasingly perplexing and degrading. What might it take to readjust current trends for the benefit of the viewers and the viewed?