A view through the trees along the Circle Trail

The snow is slowly retreating from the mountains above Santa Fe, although winter never gives up without a fight in the Rocky Mountains. There was a dazzling new coat of white on the high peaks only a few days ago, revealed the morning after a chilly and unwelcome flurry down here in town last week. But the spring runoff is in full force, the authorities are letting water out of the reservoirs into the little Santa Fe River, which is burbling happily across the street from the Inn, and the aspen and river birches are confident enough to put out fuzzy tassels in the lower reaches of the forested canyons that lead you into the Santa Fe Range.

This means it’s time to have some walks on the trails at the middle elevations above town. Sure, you’ll have to pick your way through a few wet snowbanks in the shadowed clefts, but it’s obvious the forest is shaking off its winter slumber:

Bright green kinnickinnic coming out from under the covers

And believe me: you can get a memorable sunburn hiking this time of year. Don’t forget the sunblock!

The abundant runoff prompted me to make the short 8 mile drive up from Santa Fe to Hyde Memorial State Park, to check out the waterfall I wrote about earlier, back in the depths of winter. But before doing this, I decided to hike the Circle Trail, on the south side of the road that divides the park into two sections. This pleasant trail, which passes though a classic section of the mixed conifer forest of the southern Rockies, is little frequented, because you have to pay a small $5 fee for day use at the State Park, and most local hikers simply opt for one of the numerous free trails in the Santa Fe National Forest.

Some interesting local history

There are surprisingly good views along the way, considering that you’re only about halfway up the road to Aspen Vista and the high country trails that leave from Ski Santa Fe:

Yes, that’s fresh snow on Big Tesuque

And of course I had an underlying motive to hike this way: rocks! Hyde Memorial State park straddles an ancient fault in the rugged crystalline rocks exposed in the Santa Fe Range, and I wanted to compare the outcroppings on either side of this important local structural boundary. Hyde Park marks the place where you leave the foothills of the mountains, so to speak, and enter the loftier regions, and as always, there is an underlying reason for the change.

There is an excellent description of the Park’s geologic setting by Shari Kelly, one of our prominent local geologists, here, and I urge you to have a look when you have a moment. As I mentioned in last week’s entry, rocks that are often simply lumped into the generic category “the crystalline basement” or “the Precambrian basement” because of their tangled and brutal history, can reveal some amazing insights upon closer examination.

The dominant component of the crystalline rocks in the Santa Fe Range are granites and other related igneous rocks, rather than the metamorphic rocks I wrote about last time. Everyone is familiar with volcanoes and all their pyrotechnics, and can picture ash falling out of turbulent clouds over Iceland (and clogging jet engines!) or lava flowing into a seething ocean off Hawaii. These are volcanic rocks, the output of Vulcan’s forge. But there is a deeper, hotter, more hellish realm, the domain of the dark god Pluto, and the molten rocks that crystallize here, miles below the surface, are called the plutonic rocks.

Because they form in similar environments, plutonic rocks and metamorphic rocks are intimately related. And of course, to confuse matters, igneous rocks are just as subject to metamorphism  as any, and most of the granites in the Santa Fe Range show clear signs of reheating and strain. Here is an outcropping on the south side of the Borrego Fault zone, a very fine-grained, light-colored granite with little quartz “eyes” that were elongated by shearing forces:

Quartz porphyry along the Circle Trail. Penny for scale.

When you cross the road to climb up and have a look at the waterfall, you find an entirely different look:

Foliated biotite granite just below the waterfall in Hyde Park

This granite is far more visibly crystalline than the one on the south side of the park, and its metamorphism is clearly shown by its abundant and strongly aligned flakes of the black mica biotite.

These are the strong rocks that begin to hold up the higher peaks in the Santa Fe Range. There are more complications above – and even higher summits – but I’ll spare you that story for another time.

Oh – the waterfall. The ice is gone now, and this tiny tributary of the Little Tesuque River is singing in its new freedom:

The waterfall in Hyde Memorial State Park, cascading down a bowl of foliated granite

So start planning a few hikes for your upcoming visit to Santa Fe. The snow is leaving and it’s time to hit the trail.  And to “look at all the sparkly rocks, Mommy!”, as I heard a child up at Aspen Vista exclaim, while you’re at it.

A “sparkly rock” along the Circle Trail, with a shiny penny for scale