Astro 25: Field Astronomy in the California Mountains - Limestone Caverns and the Fall Milky Way in Sierra Gold Country

Oct 13-15, 2017

Post-Trip Photo Page


This field astronomy course will keep us busy both staring upward at the universe, and staring deep underground at the amazing geologic processes happening in limestone caverns. With the recent discovery of possible running water and also limestone formations on Mars, the processes we'll study here may happen more widely on other planets.

Here's a link to the formation of Caverns. We camped near here and explored the caverns as part of Astro 28X back in Spring '08. Check out the photos from that adventure. Farther up Hwy 4 back in '01 for Astro 28E; before I was so meticulous about digital photo-recording everything. However, check out the pix I did get at the link.


Our campground is likely going to be at Sourgrass Campground/Wakaluu Hepyoo Campground at Sourgrass Crossing of the Stanislaus River - that's where we camped last time. It does not look like reservations at this time of year are possible, so I will want to get up there ASAP on Friday to grab spots. Anyone (Kirk? JP?) wanting to come a little early and help on that are extremely welcome to do so! Pictures and details to follow...

My Astro 28X class at California Cavern, Spring '08.




In the Rock Shop, ready for the descent

Directions to get to our campground.

Get onto Hwy 4 going into the Sierra and pass through Arnold up to Dorrington. At Dorrington, look for Boards Crossing Rd. The Google Earth 'streetview' image of the intersection is below. Turn right onto Boards Crossing Rd, which winds through residential forested area and then splits into Forest Rte 5N02 and Boards Crossing. You want to take the left branch = Forest Rt 5N02, which leads to the campgrounds on the river after another ~2 miles. However, note that it's possible at thie no-reservations campground that is may be full before we get there, in which case our second choice is the Boards Crossing campground a couple miles back up and then down the road you came in on, down to "Boards Crossing" primitive campground. It would be a good idea to bring enough water for your personal needs in case we end up there. Here's the map

Here's the turnoff as you come up Hwy 4 at Dorrington, to turn right and head down to our campground possibilities

The map to our campground possibilities. #1 is the upper area, with the Wakaluu Hep Yoo campground and SourGrass Campground. If those are full and you don't find me, I will try to post a note on the message board and tell you to go back up to the "Y" and down Boards Crossing Rd and we'll be at the Primitive campground, which has bathrooms but water will be our own.



Google Earth view of our Sourgrass campground and telescope viewing area.

The Stanislaus River near the bridge

Another shot near our campsite

Our secondary camp area is at the bottom of this image at Boards Crossing. It's dispersed camping, which means we just occupy what we want. There may be other campers here as well.



Arrive at our campsite by around 6pm; I'll fix you a fine pasta dinner. Volunteer contributions of veges and salad makings welcome. We'll stoke up the campfire (if permitted, fire season has been baad) and enjoy a short lecture around the warmth about what we're going to be observing. Then, bring out the scopes and study the galaxies and planets that grace the Fall evening sky. Saturn will be high overhead, . The great Andromdea Galaxyis high. in the east. Our little "Local Group" - consisting of the Milky Way, Andromeda, and a posse of little groupie dwarf galaxies, are on the outskirts of the Virgo Supercluster (cluster of clusters!) of galaxies. Bring your chocolate chip cookies to enjoy around the scopes! Our astronomy club members Kirk B and JP Lane are planning on joining us with their monster 12" and 25" Dobsonian telescopes, and probe for distant quasars and some of the farthest objects possible for any amateur astronomer to ever see, BILLIONS of light years away!

Saturday Plan

7:30am Breakfast: As with all my Astro 25 field trip classes - we begin the day with my famous French Crepes breakfast. I'll get up early and begin the preparations of the batter. Help in carving fruit and we'll make it a communal experience. Breakfast will be leisurely, next to the river.

10:30am After we clean up Breakfast, we'll carpool / drive the 45 minutes or so along the picturesque winding roads a few miles northwest of Arnold for a guided tour of California Cavern labelled "Cave City on your map. We have reservations for our group tour of California Cavern (my favorite, compared to Moaning Cavern) requiring us to be at the Cavern shop at 12:30pm at the latest. Students are responsible to pay the $11 fee - ( Group discounts for school groups are $11/person, a deal vs. the regular $17!). That's in addition to your campground and meal fees. Please bring $11 cash and I'll collect it at the Cavern shop (thanks to Carol Lee!) and give it to the guide so we can begin the 1pm tour.

Directions to California Cavern.
Follow me in the Cabrillo College Van and / or use the maps here, which I'll staple together as part of our "map package" when I see you on-campus Oct 7. Coming up from the campground and onto Hwy 4, we drive down the mountain, looking for Avery-Sheep Ranch Rd, onto which we turn right....


Here is where we turn right, onto Avery-Sheep Ranch Rd. From here, it's 17 miles and 40 minutes to the Californina Cavern

Stay on Sheep Ranch Rd as it winds through the hills and "T" ends at Sheep Ranch Rd. Turn right onto Sheep Ranch Rd

Stay on Sheep Ranch to Mtn Ranch, and turn left, and left again on Cave City Rd to California Cavern State Historical Monument at "Cave City".

Mapquest Route. Might be a little slower on a Friday afternoon, though.


Depending on how much time we have in the afternoon, we might want to take a side trip after the cavern, to do a 1 mile hike to this fascinating place, where Coyote Creek disappears into a giant limestone hole. It would mean turning right (downhill) instead of left (uphill back towards camp) when we get back to Hwy 4 driving back from the cavern. We'll decide that after we exit the cavern or perhaps before that.

Natural Bridge Creek, disappears into a hold, but you can swim to the other size, 30 yards away, and when we were there, airspace above the whole way (we didn't do it, talked to others there)

Map to Natural Bridge hiking trail. It's also the way towards Moaning Cavern, which we visited back in '08



Our goals: Study the process of precipitation and calcium carbonate formation. I'll connect this to how we can determine the tipping point for the melting of the Siberian Permafrost in paleo climate. Very clever, ingenious idea worked out and successfully carried out by by Dr. Anton Vaks and his team 4 years ago. This is a key piece of science showing how serious our current climate change future will be.

Then, if there's time, another drive further up Hwy 4 to a location where we can see a rare outcrop of the original, 100+ million year old volcanic mountain range that preceeded the formation of the Sierra and discuss how volcanoes on Mars and Earth may be connected by similar processes. More likelly, we'll explore the Stanislaus River canyon. We'll study glacier and water carved granite formations and lecture on the processes that shape canyons on Mars, the Moon, Mercury, Titan, and Earth. I'll also lecture on the Milakovitch cycles and their grounding in the semi-chaotic nature of gravity in the solar system, the last great Ice Age, evidence for a giant comet impact at the end of the Ice Age. If it's warm enough, we'll have some relaxation time swimming in the river.

At the telescope; we'll use our computer-controlled 8" scope to direct us across the heavens' best study objects

Saturday evening - Another great campfire dinner! Likely an Asian theme'd jasmine rice and vege's creation. Then, at 7:34pm, the International Space Station rises in the NW, passes right overhead reaching magnitude -3.8 - as bright as Venus! - and then sets in the SE at 7:39pm. Worth watching, and maybe a photo-op for enthusiasts.

Follow up with more telescopic explorations of the evening sky. Contrasting galaxy types, nearby star clusters and the structure of the Milky Way disk that we live in. Late in the evening, the incredible objects of the Fall Milky Way and the Sagittarius Spiral Arm will be in the West, and the supernovae remnant Veil Nebula high overhead. We'll study the birth (in luminous emission nebulae) and death (in a final exhalation of their last breath) of stars, with the Ring, Owl, and Dumbell nebulae.

Sunday Plan

Another fabulous breakfast creation - this one centered around eggs and simmered black beans and vegetables with cowboy toast. Then, we'll aim the 8" scope w/ filter at the sun and I'll lecture on the solar cycles, their relation to sunspots, and to Earth climate. We may do one more hike. I'm working on that. It would be short.

Before we leave camp, I'll hand out the take-home final exams (you'll have ~10 days to finish and return to me). I'm also checking on locations which might be worth a stop on the drive home. My thought is to drive through Calveras Big Trees State Park and enjoy the giant Sequoias - largest organisms on Earth. Either way, you should be back in Santa Cruz by late afternoon if you have studying to do, so no worries.



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