The spring you see in the picture at the left, flows out of the hillside near the west bank of the Pecos River at Terrero, NM. The flow rate varies during the year from less than one cubic foot per second up to around five cfs. The spring is in a limestone formation, whose name I am not sure. The geologic map for the Rosilla Peak quad is in draft form and hard to read. It doesn't include much detail in the mapping on this hillside, either.
There are also caves just around the hillside (fenced) that have cultural significance to the Jemez Pueblo; when the Pecos Pueblo was so decimated by disease there were few people left, the remainder joined the Jemez. The Jemez were trying to purchase and remove access to this tract (owned by the state, now) some time ago; I'm not sure if they are still working on it.
When the flow increases, occasionally there is some local hullaballoo about cars driving through the spring flow across the road and increasing turbidity and the sediment load in the Pecos, into which the spring flows, albeit through a very nice wetland complex in between the road and the river (just outside the field of view to the right of the photograph to the left). The increased turbidity in the Pecos is not a good thing, and it does piss off the fishermen and women who have likely traveled a ways to get to what is known as a very good trout fishery.
Occasionally, someone will bring up an earthquake somewhere that occurred just about the same time the flow increased. Local knowledge puts it that the flow increase is sourced much more locally (upstream a ways). The rationale is that the flow has, in the past, included fire debris from a canyon about 1/2 mile to a mile upstream that did not occur any further upstream on the Pecos. Presumably, the flow pathways through the limestone include a source in or near that canyon. (Did that make any sense? I'm still a little under the weather.) Nobody knows for sure, as no hydrologic studies have been done on the spring of which I am aware.
It's a lovely spot, and well worth a visit. Just drive up the canyon almost to Terrero, turn left up Holy Ghost canyon, turn right and cross the creek toward the campground, and you'll cross the spring flow in a very short distance.