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It's a little difficult to make out the old shorelines of Lake Lahontan in this photo. I'm sure it would have been better earlier or later in the day when the sun was lower and the shadows more distinct.
Lahontan was a large lake formed during the cooler period that followed the last glaciation and it filled much of the area between the mountains in western Nevada 10,000 years ago. It lingered at lower levels much later than that and the petroglyphs at Grimes Point are carved into boulders that would have been scattered around the edges of of a shallower lake several thousand years later. Or at least that's how I understand the story.
Gilbert did some classic work on the spits and other landforms that formed on the shores of Lake Bonneville, but I haven't done my homework and don't know how much has been done on the shorelines of Lake Lahontan (although I'm pretty sure shorelines features and beach ridges have been described).
Nevada Beach is a long strand of coarse red sand, very different than the landscape at Sand Harbor. It's located at the southeast corner of the lake and appears to be the result of sand moved eastward, possibly from stream sources along the south shore shore of the lake. The backshore is wide and suggests a very long period of sand accumulation (or a lot of human intervention that I'm missing). From the shape of the beach, I assume the dominant wind and waves impacting this stretch are westerlies - it just seems like this shoreline would look very different if northerly wave action was a significant factor.
AERIAL VIEW
As usual, my observations are based on awfully limited experience and virtually no research, so I apologize if I've got the story wrong. All my searches for information on Lake Tahoe beaches went to tourist sites and vacation rentals, not shoreline geomorphology, although I can't imagine that some geologist hasn't found an excuse to spend a summer or two studying these beaches.
100 years ago, Sand Harbor was a place to load logs onto boats headed for the mill. Now it's the primary beach access for Nevada's Lake Tahoe State Park. The small bay is actually a pocket beach tucked into the north side of a bouldery point. There is a much broader beach on the south side of the point. The orientation of the beaches at this northeast corner of the lake - here and just north in Incline Village - matches the large fetch across the 22-mile long lake.
AERIAL VIEW
I love the juxtaposition of the rounded boulders with the deep blue water. The beaches on the lake seem to range from white to pink - which I suppose reflects the variation in the granitic rocks from which they were eroded.
I made a mental note to come back sometime and spend a lot more time exploring the beaches around the rest of the lake. On this trip, I had to stick to a fairly tight schedule and to the east side.
Overton Beach is a boat launch way up on the north arm of Lake Mead. At Boulder Beach, the waves were able to build small beaches, but not erode the shoreline itself. Here, the shoreline is steeper and the lake has cut a series of subtle strandlines and one not so subtle scarp. I suppose the height of the bluff reflects both the length of time that the lake remained at that particular level, the magnitude of storms that occurred during that period, and the steepness and erodibility of the shoreline itself. Here, the shoreline is on a pair of projecting ridges that appear to have been built as breakwaters when the marina was created, so they consist of nothing but loose gravel.
My challenge during a long weekend in Las Vegas (more pictures at hshipman) with lots of extra time on my hands was to find some beaches. Of course, that usually begins with locating water bodies, which around here narrows the search awfully quickly. The first candidate was at the Mandalay Bay, where the pool offered hope of artificial waves and a simulated beach. But it was closed for the season and the photo over the fence isn't worth posting. The next attempt was at Lake Las Vegas, since the Ritz Carlton advertised a white sand beach, but though we walked the shoreline, there was no beach to be found. Maybe you have to be a registered guest.
Lake Mead, on the other hand, does have beaches, although with the lake falling about 10 feet per year since the late 1990s, they don't have much time to form before being stranded. At Boulder Beach, the lake is retreating down a gradually sloping alluvial fan and given enough time in one place, the waves can form small beaches. These gravel barriers were neat, separating small puddle lagoons from the rest of the Colorado River. Occasionally higher waves would spill over the top of the berm, carrying gravel down the backside to form little overwash fans.
