Finding Gold in the Mother Lode (but not that kind): A bit of color in drought-stricken California

Our search for gold in the Mother Lode of the Sierra Nevada foothills was successful, but we weren't looking for that kind of gold. Yes, these gentle hills once hosted one of the greatest gold rushes in history, but the mines have been silent for many decades. Today, the Mother Lode is a tourist destination, and one of the attractions is the spring wildflower show. In the last post, we saw how a few endemics are showing up this week on the serpentine soils in the Red Hills Area of Critical Environmental Concern. Serpentine occurs in bands associated with the Melones Fault Zone which divides two major terranes, the Calaveras Complex and the Foothills Terranes. The Mother Lode gold-bearing quartz veins occur along this same boundary.

Highway 49 winds for 150 miles or so along the Mother Lode, and as we saw in the last post, the early flower shows are patchy, and are helped in places by runoff from the asphalt. The hills are green for the moment, but the green will not last long. In most normal years, 90% of the rain has fallen by now, and we have received maybe 25% of the rain we usually expect. It's the worst drought ever recorded. The green grass in these pictures will start turning brown in a few short weeks, and we can look forward to a hot, dry and fiery summer season.

So the early wildflowers are out, and if the expected storm arrives tomorrow, they might receive enough water to last a few more weeks. One thing I know from years of exploring southwest deserts, flowers in a dry place are precious to behold. So enjoy some of the color we discovered last weekend.

 There were occasional patches of Foothills Poppies.

The Redbuds were in bloom, adding bright splotches of purple or pink to the hillsides.

 Lupines seem to do well in lots of environments along the Mother Lode.
These pleasing-looking leaves are not good for touching or picking; this is the ever-present Poison Oak. The leaves are colorful and eye-catching throughout much of the summer season and into the fall.

We reached the Moccasin Creek area and saw where the Marshes Flat Road diverges from Highway 49 and heads west through the metavolcanics and metasedimentary rocks of the Foothills Terranes. These Jurassic rocks were deposited on the sea floor and scraped off into the vast subduction zone complex that once extended from Canada to Mexico and beyond. Today the rocks are tilted to an almost vertical attitude. On the meadowlands around Marshes Flat the rocks are rarely seen, as they are covered with fairly deep soils.

The road is a pleasant backcountry avenue that serves as access for several ranches. It's usually an uncrowded drive.

The metavolcanic rocks show up when the road starts down the steep slopes towards Don Pedro Reservoir. Although there was almost no water in the creeks, some of the slopes had pockets of blooming flowers, including these Shooting Stars.

 If these are Shooting Stars, are the two flowers below star-crossed lovers?

 Near a creek we found some wild onion blooming.

 And a moving rock. Seriously, why is there a track here, and what moved the rock?

We saw that the sun was getting low in the sky, and I had a lot of grading to attend to, so we headed home. I hope the blooms last long enough for another trip before summer sets in!

The Other California: Springtime along the Great Western Divide

Lupines along the Kaweah River gorge (Moro Rock and Alta Peak in the distance)

The Great Western Divide? Where's that?

My off and on blog series on the Other California is an exploration of the little-known places in my fair state with interesting, even fascinating geological features. Sequoia National Park might seem too familiar a place to be included as part of the "Other California", given that my own definition of the series is that it should include those places that don't normally show up on postcards, and Sequoia National Park certainly does.

So why include Sequoia? The primary reason is that it actually is less known than other parts of the Sierra Nevada. Ask folks where they go in the Sierra, and Yosemite Valley or Lake Tahoe are often the first places mentioned. And people often come to the park not so much for the geology, but for the biology, mainly to see the trees after which the park is named. But the park has a rich geological heritage as well.

Moro Rock from the Kaweah River gorge

The shape of the Sierra Nevada is often described as a tilted block of granitic rock and metamorphic rocks. That's true in the Sierra Nevada north of Sequoia. Driving to Yosemite National Park from the west involves a gradual climb up the western slope that continues to the Sierra Crest before dropping precipitously into the Owens Valley or Mono Lake on the east. Sequoia and the Southern Sierra Nevada is quite different. When one arrives from the west (which actually is the only way in which the park can be approached by roads), the road climbs steeply to a plateau, and the slope continues to a high crest. But not of the Sierra Nevada. It's an entirely separate mountain ridge called the Great Western Divide. The actual crest of the Sierra Nevada lies farther east, across the deep gorge of the Big Arroyo and the Kern River.

The Great Western Divide is a spectacular mountain range. It rises nearly to the height of the actual Sierra Crest, with several peaks exceeding 12,000 feet in elevation (A dozen or so peaks on the Sierra Crest reach 14,000 feet). Despite being far to the south, the peaks were high enough to be scoured by the glaciers of the Pleistocene Ice Ages.

A few weeks back we had the chance to pay an early springtime visit to Sequoia National Park. We came in from the west, up Highway 198 along the Kaweah River through the town of Three Rivers, and then up the Generals Highway to the Sequoia groves for which the park is justly famous. The road is notably curvy, and climbs through a rugged canyon choked with giant boulders that have tumbled from the cliffs above.

We soon passed one of those kitschy things that Civilian Conservation Corps workers in the 1930s seemed especially fond of constructing: a drive-through rock (to go along with "drive-through" trees). They enlarged the opening under the immense boulder, and put the road through it.

If one wonders why the road today circumvents the rock tunnel, one need only look at the underside of the boulder. People driving in scenic national parks are not known for paying close attention to their driving, and in a time of massive recreational vehicles, this kind of thing just doesn't cut it anymore.

A hat tip to the arrival of spring in the Sierra Nevada...the redbuds were in full bloom up the canyon, providing a splash of vivid color on the dark green slopes.

Although not as colorful as redbud, the ceanothus shrubs added a wonderful fragrance to the air. The bees and other pollinating insects were in heaven.

As we went further up the canyon, Moro Rock loomed ever higher above us. The granite rock of the dome expanded as the rock was exposed at the surface. The plutonic rock tended to fracture parallel to the surface, which had the effect of removing corners and edges from the rock outcrop, eventually leading to the formation of the dramatic dome. The process is called exfoliation. It would be so cool to climb the dome, but we knew that most of the park access roads would be closed because of the winter snowpack.

Except that they weren't. When we reached Giant Forest, there were a few snow patches here and there, but the snowpack is currently at half the normal level. All the roads were open, so we headed over to the Moro Rock trailhead. As dramatic as the dome is, trail access is easy because the CCC put in a stairwell to the summit. Easy that is, if you don't have problems climbing 300-400 steps. The views in the clear spring air were stunning.

Immediately across the Kaweah Gorge were the Castle Rocks (9,000+). The spires and towers of granitic rock exhibit the other result of rock expansion: jointing. When the fractures that result from pressure release are vertical, they allow water to get into the narrow spaces. If the water freezes it expands, wedging the rock apart. The water also aids in the chemical weathering of the rock, so as time goes on the cracks widen, forming the prominent spires.

Moro Rock is best known for the wonderful perspective it provides on the Great Western Divide. The mountains are often hidden from view by other high ridges or thick forest, but Moro Rock stands out from the mountainside, and the view is tremendous.

With the covering of winter snow, one can imagine the glaciers that carved the horns, aretes, and cirques that are so well exposed here. Cirques are the bowl shaped basins on upper ridges where the glaciers accumulated. Aretes are the knife-edged ridges that divide glacially carved valley, and horns are the sharp pointed peaks that result when glaciers pluck rocks from the base of the cliffs in the cirques and aretes. The Matterhorn in the Alps is a familiar example, but there are many horns to choose from on the Great Western Divide.

I have not yet had the privilege, but the High Sierra Trail winds its way from Crescent Meadow in Sequoia to the summit of Mt. Whitney and the Whitney Portal trailhead. It is 60+ miles long, and crosses two major passes, and it must be a marvelous adventure. It is second only to the John Muir/Pacific Crest Trail in popularity.

The picture below illustrates the difference between glacial erosion (the cirques and horns in the upper part of the photo), and the weathering and exfoliation that happens at the lower elevations (the domes both right and left of center).

Moro Rock also provides a wonderful view west towards the Sierra Nevada foothills and the usually invisible Central Valley. You are looking at the most polluted air in the United States: Bakersfield and Fresno. It's not entirely their fault, as they don't necessarily produce more pollution per capita, but the towns are surrounded by high mountains, so they can't blow their pollution into someone else's area the way other municipalities are able to. The photo below is as clear as I've ever seen it from Moro Rock.

Next, we took a look at some trees with a unique geologic history...

Three Roads Diverged...but why? Because there's a huge landslide, that's why...

It didn't take Ron Schott long to reveal why three roads diverged in the wood, the subject of yesterday's post on Highway 41 heading into Yosemite National Park. The Ferguson Slide was a problem child for CalTrans and road management crews for many years. The orientation of the river and the dip of the metamorphic rocks on the high ridge conspired with the undercutting effect of roadbuilding to destabilize the slope above the highway (you can see some of the slide activity in this video). The slide permanently covered the highway, and the first temporary bridge did not allow larger vehicles to make the 90 degree turn. Bus tours are the life-blood of the local economy, so the current bridge crosses the river at an angle so longer vehicles can cross safely. I blogged about the slide last year, when I compared the Ferguson slide to a different kind of mass wasting event just inside the park boundaries.

The fix is still temporary, with only a single lane available, so delays are common while cars wait at both ends. A more permanent solution is the subject of extensive studies, which can be reviewed here.

We had to wait at the slide both coming and going home from Yosemite yesterday, so I was able to hop out and photograph a couple of the emerging springtime wildflowers. It was cold and dreary, so most flowers weren't doing much (it had actually snowed the previous day), but a few Indian Paintbrush flowers were visible, and the redbuds were spectacular all up and down the Merced River Canyon. I really want to head back up in the next week or so, and see the poppies and fiddlenecks mantling the high slopes.

But, you ask, how was Yosemite? Spectacular in a different way. Coming up in a future post!

Random Thoughts on Yosemite in Spring

My last couple of posts on Yosemite in springtime followed a theme of some sort, rockfalls or waterfalls and such, but I also just plain saw a lot of beauty derived from the bounty of water at this time of year. The nice thing about a place like Yosemite (and any other kind of park) is the richness of color and texture in features big and small. The picture above is of some redbuds that are still blooming, along with a groundcover teeming with flowers of all kinds.

It was raining prior to our arrival...moisture was everywhere, including the droplets on the clover by the highway where we looked at Grouse Creek Falls. The clouds were moving eastward ahead of us, giving an interesting perspective to the little noticed cliffs around Stanford Point (little-noticed because everyone is looking east to El Capitan, Half Dome, and Bridalveil Fall from the Tunnel View parking lot. It's one of those cases where these cliffs would be world-famous if they were located anywhere else.

Half Dome was putting on a show today, too. This view from the Curry Village parking lot is hard to miss, although I almost always get a telephone wire in the picture. Whose idea was it to string a telephone wire across the view of one of the most iconic rocks in the American West?

Tenaya Creek was running full, and will deserve an entire post of its own in a day or two. The water is strikingly clear, primarily because the watershed above has been stripped almost entirely clean of soil by the glaciers that coursed through the canyon as recently as 13,000 years ago. The water flows over barren rock over much of its course and thus carries relatively little sediment.

One more waterfall to add to the mix. This is Royal Arch Cascade, which tumbles down the canyon wall just west of the Arch. Most people don't see this particular view, as it is a zoom view of just the very top of the waterfall.

It is easily viewed from the parking lot of the Ahwahnee Hotel. We had an appetizer in the bar for the price of a dinner! And it felt worth it...

As we left the valley, we made a brief stop at Valley View, another one of the iconic views of Yosemite just west of the "Gateway", the towering cliffs of El Capitan and Cathedral Rocks. Jet contrails usually screw up pictures of nature, but there seems to be a kind of symmetry to the ones seen here.