El Morro Trails: El Morro National Monument, New Mexico

by Southwest Parks and Monuments Association

Here you can see at close hand the difference between the dark, upper layers of ocean sands and the light color of the lower and earlier stream and dune sands. Look here at the cliff above you and a little to the right. The lower is Zuñi sandstone, of the Jurassic period, and forms the bulk of El Morro. The upper is Dakota sandstone of Cretaceous period, representing beach deposits of the ancient sea which covered all the area. The contact surface between these two units represents a time interval of between 25 and 50 million years when erosion instead of new deposition was taking place.

6.

Look on the left side of the trail and a little behind you. You will see a dark green stake that marks one of the four corners of the unexcavated ruin. Let your eye follow along the top of the incline to your right and you will see another green stake, another corner. As you follow the trail on this side of the box canyon, look to your left for the last two stakes and you can tell how big this ruin is. Please do not leave the trail.

This village was possibly two or three stories high, but after the Indians left, the roofs collapsed and the walls fell in. Then the sand blew in, weeds began to grow, and you see the result.

7.

Looking at the cliff wall across this little box canyon, you can see a definite horizontal line about half way down. The materials above and below the line were laid down about the same time, but the line represents a layer of softer material which has weathered away faster.

The reason for the unevenness is that stream channels cut into the underlying sandstone, and then, as the land slowly settled to allow the sea to encroach, the channels filled up with sand. The sands were reworked by waves on the beach and the tops smoothed out and leveled. Small lagoons and swampy areas formed along the coastline. As you climb the steps at [No. 11], you will cross a small seam of coal-like material which was formed from one of these swamps.

The geological disconformity described at [Stake 7].

If you look across the box canyon, on the horizon you will see the ruins of another village. It was occupied about the same time as the one on this side of the mesa.