A Day of Celestial Equality: the Vernal Equinox

The Earth has survived another winter and today we entered into the season of spring. I had a fortuitous moment, driving home on an east-west road (Claribel in Stanislaus County) at the moment the sun met with the horizon. In that moment, everyone on the planet who was looking saw the sun set in a due west direction. The day was just over 12 hours long, roughly equal to the hours of night.

We are currently about 93 million miles away from the sun at this point, but our orbit is currently carrying us a little bit farther away. By July 4, we'll be about 94.5 million miles away, the aphelion. We are the closest to the sun, about 91.4 million miles, on January 3. That day is the perihelion. If that relationship seems counterintuitive, it's because the seasons having nothing to do with our distance from the sun. It is the 23.5 degree tilt of the Earth's axis in relation to the sun.

Source: NOAA

The pole of rotation always points to the same place in the cosmos, near the North Star, but at different times of the year, the journey about the sun finds the northern hemisphere tilting towards the sun (summer), or away from the sun (winter). In spring and fall, the northern and southern hemispheres are equally lit by the sun. The seasons are opposite in the southern hemisphere.

The day was distinguished by a second celestial event, a full "supermoon", the first time the two happened in the same day in nearly two decades. It won't happen again until 2030. There's nothing mysterious about a supermoon, it's just a time when the moon's elliptical orbit brings it closer to the Earth so that it appears 14% larger and 30% brighter. It's called the Worm Moon because this is the time of year when worms begin emerging from the ground as the days grow longer. We had a stormy day so our view of the moon was wreathed in clouds tonight.

I hope you will enjoy our coming journey away from the sun!

Spring is Coming, and Flowers are Awakening in the Sierra Nevada Mother Lode

It's still a bit early to see the awesomeness to come, but the spring wildflowers are beginning to make a splash of color in the Sierra Mother Lode. With the record and near record amounts of rain in Northern California, the slopes are primed to produce a wildflower show to compete with the "super-blooms" taking place in the California deserts this year. We were exploring a portion of the southern Mother Lode in the vicinity of Mariposa and Coulterville yesterday, and I took my attention off the rocks for a few moments to catch some pictures of the early-blooming flowers. Above is a Fiddleneck (Amsinckia species), often one of the first of the wildflowers to bloom in this region. It can be poisonous to livestock, and yet was used as a food and medicine source by Native Americans.

Near the Pinetree-Josephine Mine we saw a number of Brodiaea, or Blue Dicks (Dichelostemma capitatum). These beautiful flowers grow from bulbs that were also an important source of food to the Native Americans of this region.

I don't know as many wildflower species as I should, as much as I appreciate their beauty. In a few places there were carpets of small yellow flowers (Goldfields, in the Lasthenia genus, thanks to Siera Nystrom in the comments).

Seeing some of the flowers growing in the usually poisonous serpentine soils reminded me that it is time to head up to the Red Hills soon, a Mother Lode locality known for a large number of endemic species.

As per Jane Strong in the comments, Orobanche fasciculata, clustered broomrape. Thanks for the identification!

And finally, the ever-present and always beautiful Indian Paintbrush (Castilleja species). There are some 200 species of this flower.

This is only the very beginning of what promises to be a wonderful year for wildflowers. I hope to be bringing many more such scenes to your attention in coming weeks!

The Great Drying Has Begun: Springtime in the Sierra Nevada

It may seem paradoxical to speak of drought in California right now. The snowpack in the Sierra Nevada is running nearly 200% of normal, and farms are receiving the most irrigation water they've seen in years. Yosemite waterfalls are thundering. Yet that is what is happening this week, just as it does every year. The great drying has begun; the subtropical belt of high pressure, which maintains the aridity of places like the Sahara and Australian Outback, is making its presence known here in California. Despite the overwhelming amount of precipitation this last winter, we'll see hardly a drop of rain anytime between now and next October.

Even though the high country is still encased in a mantle of snow, the grass is dying here on the floor of the Central Valley. The low foothills are turning brown, so we headed a little higher, where spring is still happening. Marshes Flat Road climbs out of the Don Pedro Reservoir area onto a resistant ridge of metamorphic rock called the Penon Blanco Volcanics. These rocks formed as volcanic islands in the Pacific Ocean in Jurassic time, and were pushed into the western edge of the North American continent in Cretaceous time and scraped off to become part of what is called the Foothills Terranes. The road reaches elevations of 1,800 feet or so before crossing the ridge into the Mother Lode region at Moccasin.

The rocks are mostly greenstones, and are shot through with occasional quartz veins, as can be seen in the picture above. Oh wait, is that a flower of some sort? We've discovered spring again! It's moving uphill right now, and will take all summer to reach the alpine peaks at 12,000-13,000 feet. That is certainly the fun of living in this state. Even as the valleys dry out and bake in the dusty heat of summer, the mountains still get a certain amount of orographic (rain shadow) precipitation and remain green through September.

As I've mentioned before, I have no qualms about making my students learn the names of a couple of dozen minerals, but I have never learned more than a few flower names during my travels. In my own perception, then, I might see flowers every year, but without learning their names, they seem like a new discovery. That's fun in a way, but it is also an appalling form of ignorance, so I'm undertaking a personal project to learn the names and nature of some of the flowers I am seeing this year. So, the hardy succulent in the picture above that survives in the cracks and fractures of solid rock where almost nothing else can grow is a Live-Forever(Dudleya cymosa, corrected with Neil's help). I've seen them before and wondered how they survived, but it seems clear that they store the moisture in their leaves, rather than drawing moisture from the ground.

I'm pretty sure I've never closely observed these striking scarlet colored flowers up close. I suspect that I mistook them for Indian Paintbrush in the past, but a close look this week made it clear that they are something entirely different. These showy flowers are called Indian Pink (Silene californica), or Catchfly, or Campion. None of my internet sites seem clear on why they are called Pinks when they clearly are not. It may refer to the pink at the center of the flower, or that they are part of a family of flowers that include pink varieties. The "Catchfly" name refers to sticky parts of the flower that sometimes traps insects.

In a meadow near the summit of Marshes Flat Road, we found a beautiful purple flower that seems to be a Larkspur (Delphinium species). Besides being very obvious, it is also highly poisonous to cattle.

Another flower that did not seem at all familiar was the White Fairy Lantern (Calochortus albus), which is a member of the lily family. The flowers never really completely open up (gotta make those bugs earn their nectar?).

I've seen Clover (Trifolium sp) many times in springtime meadows, but I've never really gotten down on the ground to have a closer look.

I've also noticed this beautiful small pink flower in the past (below), but never identified it. I was surprised to find it is called Wild Carnation (Petrorhagia dubia). The genus name translates to rock fissure, referring to where some of the species grow. It is actually native to Europe.

Of course, flowers aren't the only things we see. The oak trees were bright green, and quite a few Acorn Woodpeckers were flitting about. They didn't pose very nicely for me, but I got one shot that allowed me to identify this shy one.

As always, being the non-expert botanist, I am open to corrections for any misidentifications! More spring updates as I find excuses to hit the road!

Another View of Spring in California: the Central Valley and the Diablo Range

I often use this blog to discuss the interesting and strange elements of California's geologic story, and I try to emphasize the beautiful and spectacular, but I don't seem to talk as much about my home ground, the Central Valley (or the Great Valley, when we're feeling proud). It is flat, exceedingly flat, so flat as to not vary more than a few dozen feet over its 400 mile length (with the exception of the Sutter Buttes), and for much of the year it is dry, hot and dusty. During a few months in the winter we can't even see it, as the valley is socked in with the legendary Tule Fogs. For those interested in learning and seeing the natural landscape, well, there's not much of that in our valley. Only about 5% of the land surface looks at all like it did before European contact. Agricultural fields and cities cover most of the landscape.

On the other hand, there are two seasons I really like out here. In the fall before the fogs, the trees can be so very colorful as the leaves turn. And in spring, the blossoming orchards can be a beautiful sight. A couple of pictures came my way recently that provided a nice overview of the springtime in the valley and adjacent Diablo Range in the eastern Coast Ranges. Many thanks to photographer Ed Dwyer, and pilot Allan Ramsay who made these shots available to me.

The picture above shows some of the water accumulating in ponds at the San Luis Wildlife Refuge, which includes the notorious Kesterson Reservoir. The shales of the Diablo Range contain high levels of selenium, which forms soluble compounds that can flow onto the valley floor and accumulate in the soils. A shallow hardpan layer causes a perched water table in some areas, and when such fields are irrigated, the soluble material can be concentrated close to the surface where the selenium and salts interfere with plant growth and agricultural yields. In the early 1970s farmers dealt with the problem by flooding their fields, dissolving the salts, and sending the runoff into a canal that distributed the wastewater into ponds at what would eventually become the Kesterson Wildlife Refuge.

Things went fine at first when only fresh water was delivered. A variety of fish and birds utilized the ponds, but after a few years most of the water deliveries were brackish, and animals started producing deformed offspring, and others died out. The reason was not apparent until analysis indicated extremely high levels of selenium. Cattle on nearby ranches were also affected.

Ultimately the wildlife disaster forced authorities to close the reservoir and fill it with clean soils. The problem has not been solved, and today most of the wastewater ends up in the San Joaquin River where it is at least somewhat diluted.

Luckily, other parts of the San Luis National Wildlife Refuge are not contaminated, and the region is utilized as a wetlands environment that supports thousands of migratory birds and other animals.

For those who are curious about the rocks that lie beneath the Great Valley, they can actually walk through the rocks without tunneling or drilling. The rocks have been twisted to nearly vertical outcrops in the eastern flank of the Diablo Range, seen in the picture above. The rocks are collectively called the Great Valley Group, and include around 20,000 feet of mostly sands and siltstones of Cretaceous age. The Cretaceous Period was part of the reign of the dinosaurs, but only a few bone fragments of dinos are found here; the sediments accumulated in a shallow sea where the dinos didn't live. On the other hand, the rocks have been a good place for finding remains of plesiosaurs and mosasaurs, large reptilian predators adapted to life in the sea.

San Luis Reservoir is a water storage facility for the California Water Project, and is the largest off-stream reservoir in the United States (it doesn't receive significant water from the local watershed, but is supplied by the CWP canal system instead). The surrounding rocks are a chaotic mix of shale, graywacke sandstone, basalt, chert and limestone that accumulated in the accretionary wedge of the huge subduction zone that once lay off the coast of California.

Pacheco Pass is a low break in the range that funnels coastal winds, so the hills are utilized as a wind farm, providing California with some renewable energy sources.

Thanks again to Ed and Allan for allowing the use of these pictures, and to Sarah Mesenhimer-Johnson for sending them along to me!

A Fool for Fiddlenecks and Lover of Lupines

Not very geological, I suppose, but sometimes my travels and interests spill over into the biological realm. Part of the fun of springtime in the Sierra Nevada is the profusion of flowers that emerge for a couple of weeks. It doesn't take long before they dry out and lay down seed for next year, but the geography keeps the show going all summer. The Sierra mountain block rises gently to the east, and as conditions dry out in the foothills, the snow is only starting to melt in the high country. There are flowers to be seen somewhere in the mountains all summer long.

One of my early-season favorites are the Fiddlenecks in the genus Amsinckia, a small flower that blooms especially well along roadsides and disturbed surfaces in the foothills. There are around a dozen species across the American West. They're poisonous to livestock and considered a weed by some, but parts of some species were utilized by Native Americans for food and medicinal purposes. One of my other favorites is the Lupine (genus Lupinus), which grows at many elevations in the Sierra, and for that matter throughout much of the world (there are hundreds of species). Like the Fiddlenecks, it is poisonous to cattle and can sometimes be considered a noxious weed. On the other hand, some species produce a nutritious edible seed and are considered an alternative to soy beans. They also fix nitrogen in the soil, allowing other species to colonize.

The other pretty flower I noticed in this early part of the spring bloom was the one below, but I don't know what it is. Any of my flower-expert readers gonna tell me? Some kind of Brodiaea?