The Ditch - Quarteles

My plans to get a better idea where the local acequia ran below the great mound by walking the nearby farm road were dashed by the realities of life in New Mexico in February. Light snow began falling in the night and heavy clouds persisted through the morning. With no sun until noon, it was too cold to walk in mid-morning when the local paved roads are safest for pedestrians.

I retreated to my car to seek the Santa Cruz dam. As you go east you drive through three zones. The first begins as you enter Quarteles where the USGS map says the elevation is 5757'. You rise 150' to the area where suburban Chimayó begins. The elevation there is 5909' and rises to 6220' where you make the turn for the Santuario. Continuing east, the road rises another 280' before the exit to Santa Cruz Lake.

The elevation increase in the first stage is emphasized by the badlands on the left which can be 50' higher than the road. At their base, there are the familiar Tertiary sediments of the Tesuque formation lithosome B that came from the Peñasco embayment. On top, according to Daniel Koning, are glacial cobbles and pebbles composed of quartzite, granite and pegmatitic quartz.

At the point where the road from La Puebla meets route 76, the badlands rise from 5800' at the road to 5950' inland.

Across the road, the Santa Cruz river level is low, fed only by recent snow in the air and melting in tributaries below the dam. Banks of those cobbles lie exposed like beached whales, white in the winter light.

About three quarters of a mile farther down the road, the Placita Road meets route 76.

The land exposed by road builders is leaching cobbles.

Across the road, the Santa Cruz is flowing through and over the rocks.

Photographs:
1. Rio Santa Cruz at La Puebla Road near route 76, 16 February 2012.

2. Badlands at junction of La Puebla Road with route 76, 16 February 2012.

3. Rio Santa Cruz at La Puebla Road near route 76, 16 February 2012.

4. Badlands at junction of Placita Road with route 76, 16 February 2012.

5. Road cut on route 76 at junction with Placita Road, 16 February 2012.

6. Rio Santa Cruz at Placita Road near route 76, 16 February 2012.

Tertiary Hill

On the way back from the barbarian’s wash I noticed a hill that had grass growing at it’s base, but was bare at the top. Oddly it supported several junipers.

The slope wasn’t steep. Up I went.

The grass gave way to what looked like caked mud.

Only it wasn’t. I picked up a piece. It was thin rock of no particular distinction.

I continued to the top where the fragments began to take on the shape of some kind of flow over what must have once been soft mud.

If the washes were slowly revealing some previous landscape, this hill top represented how deep those sediments must have been. Presumably, the land was all at this height at some time, but the rock kept this from being eroded as completely.

The junipers had found their water beneath the slabs.

When I got home I discovered the nondescript rock wasn’t some piece of rough-textured sediment, but a slice of conglomerate, I assume from the Tertiary age. How it got atop the sediments is another mystery, if indeed the sediments are younger.

The Cone

This afternoon I went back to the cone, determined not to be fooled again by its wiles. This time I took the simple path, the one from the near wash. As I walked up the easy grade, I realized the cone might just be the tip of the hill I live on, the one that had caused so many water problems in the past.

As soon as I got close I saw that it wasn’t bare because of erosion caused by the ATV rider. It was actually stone and not some soft soil. Daniel Koning had said it was tertiary, not the more recent quaternary. The two were there to see on the slope where the grass couldn’t hold its own.

I started climbing the cone. The more I climbed, the more the top receded into a face of gravel.

I felt no overwhelming urge to make it to the top and yodel. My knees were chanting "Jack and Jill went up the hill." The view of the black mesa was quite spectacular where I stood.

On the way back down I picked up some pieces of the grey, rough textured stone for the Rock Queen.

Hopefully she can tell me what it really is, something more useful than tertiary side of the geological change.

The River Runs

Wednesday it rained, day and night.

Thursday noon when I went to the post office the river was running higher and faster, the color of caffè latte.

I thought, ah yes, of course, the river’s running. It rained. I didn’t think, I’m seeing the great shaping force of this part of the country roused from a long seasonal slumber.

I didn’t connect even though I’d spent the morning looking at Daniel Koning’s “Preliminary Geologic Map of the Española 7.5-minute Quadrangle” which shows a lopped triangle with the Rio Grande and Route 285 on the sides, the Rio Pojoaque to the south and the Santa Cruz river on the north just above where I was driving over the Griego bridge.

He shows the road near my house skirts what he labels a “geological contact.” The soils to the river side have recent alluvial origins. The ones to the east date back to an earlier Tertiary period. Since the time before the great glaciers when the river began to connect the discrete basins of the rift valley, water has been digging and padding its channel.

It’s removed or redeposited the existing tertiary sediments, or perhaps both at the same or different times, and left a boundary area that needs no geologist to recognize.

I went back to today to the Griego Bridge to see the river at the point the Santa Cruz enters. The current was slower, but the water was still carrying dirt. Gravel and sand have been deposited where the dammed and controlled water flow of the one meets the less tamed Rio Grande.

Then I drove home and looked again at that “geological contact” out the car window. You could imagine the grass as some great sea lapping against dunes. And like ladies of a certain age who once were rivals and now nod when they meet, you can only guess their pasts from the differences in their outerwear, their vegetation.