Profile of 35-foot wall, looking north, Unit 35, showing limestone fragments in Stratum 7. The 5-foot-long measure stick rests at a depth of 198 inches. Located largely outside the drip line of the shelter, the stratum is made up of talus deposits and possibly flood materials. Based on archeological evidence, it appears to be a continuation of Stratum 5 , although it is different in color and texture. Photo by Albert Redder.
Image of a bone tools from Arenosa.
Conjoined pieces of quartzite cobble, the top half of which was found in Stratum 7, the bottom in Stratum 5E. Photo by Susan Dial.
Large leaf-shaped biface, or knife, found near the bone bed at a depth of 188 inches below datum. Photo by Albert Redder.

Stratum 7: Rocky Red

Nearly four feet in thickness, this stratum consists of reddish brown sandy clay, containing many angular fragments of limestone. Cultural materials are scattered throughout, including three San Patrice and two unclassified, expanding-stemmed dart points; a bison bone bed and a fire hearth with a radiocarbon date of ca. 10,600 years B.P. was uncovered at the lowest levels.

Extending upward from the yellowish clay layer near the bottom of the shelter to the red-white spotted Sub-Stratum 8D, Stratum 7 is positioned toward the front of the cave deposit, where the interface is uneven and difficult to discern. A portion of this stratum lies outside the overhang. Horizontal fingers of cave deposit occasionally extend into this stratum, but the deposits outside the drip line are very different in texture and appearance.

For the excavators, this stratum has been somewhat of an enigma. Redder noted: "At first we wondered if this was the redeposition of another archeological deposit.  Then a broken quartzite stone was found, half in the cave deposit and half in this stratum.  San Patrice points ("Brazos Fishtails") also were found in this stratum near the 5-foot north-south line.  With these findings, we then decided Stratum 7 may be contemporary with the cave deposit and may represent a slow build up."

Roughly 5 feet west of the baseline, two small, Archaic-looking, expanding-stem dart points were found in a single excavation unit, at approximately the same depth at which the San Patrice points were recovered nearby. One of the expanding stemmed points was found in situ; the other was found in two pieces, one in the screen, the other in the wall. 

Redder wrote at the time, “I could discover no reason for an Archaic-looking point being at this depth. Clearly a long hard look must be taken at the remainder of this stratum.”

To some, these points resemble certain Late Paleoindian/Early Archaic points. Archeologist Michael Collins has suggested (based on looking at a photo) that one may be related to type Big Sandy, the other a resharpened Wilson point. The two points also bear similarities to San Patrice variants at sites in the midwest, such as Big Eddy.

Deeply buried at the base of Stratum 7 in Horn Shelter was an extensive concentration of burned and unburned animal bone, including bison, deer-sized animal, small mammals, and fish. A few chipped-stone tools, chert flakes, red ocher, and charcoal fragments were scattered among these, along areas of burned earth. Based on size and robusticity, the bison was Bison antiquus. The bones of this animal were not articulated, nor were all elements present. Portions of the bison bone were jacketed in plaster for removal.  

San Patrice points recovered from Stratum 7. Expand to see additional specimen. Photo by Albert Redder.
Shallow, basin-shaped hearth (Feature 30-4) uncovered near the base of Stratum 7 at its juncture with Stratum 3. A composite charcoal sample from the feature was radiocarbon dated to 10,600+/- 180 years B.P. As was the case with other Paleoindian hearths at Horn Shelter, the fire was built directly on the ground, with no rock. Photo by Albert Redder.
Plan drawing of hearth (Feature 30-4), shown in photo above. Note the “drag-out” area of ash and debris, where cooked food or other materials may have been pulled away from the hearth. Drawing by Albert Redder. Enlarge to see detail.
Unclassified expanding-stem projectile points from Stratum 7, similar to some San Patrice variants from other sites. Note serration and rersharpening of blade in right specimen.
A section of the bone bed uncovered near the base of Stratum 7. Photo by Albert Redder.
Plan drawing of one section of the bone bed with elements identified and coded by Albert Redder.
Bison mandible and charcoal fragments. Photo by Albert Redder.
Vertical location of the bone bed found near base of Stratum 7, as sketched in profile by Albert Redder.
Image of a bone tools from Arenosa.
Stone chopper or scraper found near the bone bed in Stratum 7. Photo by Albert Redder.
Tiny bones, chipped stone flakes, and snails recovered from water screening of sediment sample in Stratum 7.

Adjacent and west of  the bone bed, but further under the shelter overhang, was a shallow, basin-shaped hearth (Feature 30-4) with a “drag-out” area, perhaps representing the removal of cooked food or other materials from the fire. As was the case with other Paleoindian hearths at Horn Shelter, the fire apparently had been built directly on the ground, with no rock, resulting in areas of burned earth. Charcoal, a bison rib bone, and other bone fragments, some of which were burned, were recovered in or near this feature. A charcoal sample was AMS dated to 10,600+/- 180 B.P. (CAMS-395 12,438 +/-260 calibrated years B.P.

Roughly 50 pounds of soil was saved from the feature and other areas and brought back to the lab for washing in a fine screen. This yielded a quantity of tiny animal bones, burned bone fragments, stone chips, and a variety of snail shells.

The scraper, or uniface, assemblage from Stratum 7 is similar to that of Sub-Stratum 5G, except that they are not as numerous and three types—oblique, concave, and transverse—are not present. One end scraper was found.  Other chipped-stone tools were scraper-gravers, utilized flakes, biface fragments, a core, and a chopper.  Worked and polished bone fragments were found, as well as charred bone.

Stratum 7 is likely a buildup of deposits (talus) that have been washed over the top of the shelter, and includes regolith and red soil from the Edwards formation. The talus deposits may have been mixed as well with some flood silts and sands.  Based on the occurrence of the very early hearth, the San Patrice points, and the refitted quartzite cobble fragment, this stratum appears to contain several occupation areas equivalent to, or outside extensions of, the cave deposits (5G). These may be more clearly defined after further analysis of the materials and records. Like the interior cave deposits, Stratum 7 is capped in part by Stratum 6, a deposit which contained a Scottsbluff point and an unclassified expanding stemmed point. 

Examples of unfacial tools, modified animal bone, and other materials from Stratum 7. Photo by Albert Redder.
Unifacial tools from Stratum 7.
Two large boulders found at a depth of about 198 inches in Stratum 7, at the edge of the drip line. View looking east. Photo by Albert Redder.