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.

Santa Fe Group

Santa Fe Group is a term like sparrow or hummingbird. It allows you to describe things fairly accurately when, in fact, you don’t really know enough to be specific.

Ted Galusha and John Blick say that at one time or another it’s been used to describe almost anything along the Rio Grande. They narrow the term to middle Miocene and early Pliocene sediments found between the Sangre de Cristo and Jemez.

They identify two general areas, one they call Chamita, the other Tesuque. Within the second, which is the one found where I live, they identified five major strata: Nambé, Skull Ridge, Pojoaque, Chama-el Rito, and Ojo Caliente sandstone.

The laminated formations you see along 285 when you drive through Arroyo Seco between Santa Fé and Española are from the Skull Ridge and Pojoaque members. According to Daniel Koning, the first was deposited 16.2 to 14.6 million years ago; the second is dated between 14.6 to 11.6 million years ago.

Koning also indicates that rocks came from two sources in the late Miocene. Those towards the north and west are from the Peñasco embayment between the Picuris and Santa Fe Ranges of the Sangre de Cristo, while those to the south and east generally arrived from the Santa Fe Range.

The Los Barrancos fault zone runs to the west of the highway. Sediments to the east, the ones you see, are older than the ones to the west, which are the ones that come close to my house.

The rocks on the west side of the road in the top picture are from the Peñasco embayment with the Skull Ridge member exposed in Arroyo Seco. The rocks on the east side in the second picture have the same provenance, but are older.

The third picture was taken on Pojoaque pueblo land. Koning identifies them as Skull Ridge layers from the Santa Fe range. In the picture below rocks from the Pojoaque member of the Peñasco embayment rise behind the wall of the far arroyo.