Geomorphologic Context

Eroding streams running east-northeast to west-southwest toward the Bumthang chu regularly crosscut all three alluvial terraces. Nowadays, the forested blue pine overgrowth (Pinus wallichiana) makes it difficult to follow the terrace riser edges with precision. A photograph (Fig. 7) taken by Anthony Aris in 1970 shows that the area of study had undergone an extensive deforestation of the lower valley flanks thirty years ago. This older picture gives a clear view of the 40 m and 70 m alluvial terraces and the transecting stream crosscuts.

Fig. 7

To the east of the archaeological site, a small stream, which seems to have dried out almost completely, has progressively filled a shallow channel that is still visible on the topographic record (see also Fig. 9, between B3 and B4). Nowadays, this stream brings in just sufficient water volume to make the area spongy and wet. At the terrace riser edge, the stream flows regularly during monsoon and cuts into the upper terrace riser edge.

To the east of this stream, we find a large flat grassy area used today as pasture land for cattle and horses. The pasture is limited to the east and south by blue pine forest.

Sedimentary Setting

Based on our own observations, the local sedimentary deposits of the 70 m terrace are consisting of a very thick alluvial accumulation of rounded boulder, mostly of crystalline origin, densely fixed in a hardened matrix of sand locally forming observable accumulation and erosion patterns. This layer, which is covering and hiding the gneiss bedrock, shows an impressive thickness attaining 10 meters (Fig. 8).

Fig. 8

The sedimentary mass overlaying the alluvial deposit consists in layers of yellow sandy loam of varying thickness. In some areas near the RNR-RC building site, its thickness attains more than 2.5 meters; in July 2000, we observed more than 3 meters of upper deposits in the pit dug to hold the septic tank of the new research center, near the terrace riser. The highest sediment deposit of the terrace consists in brown, humic, and slightly clayey silt. Locally, this recent soil is fairly thick due to colluvial action that, in our opinion, occurred recently and was caused by anthropic deforestation at higher elevations.

In our preliminary report for 1999 (Blumer and Vial 1999), we reported about a possible wind-blown process which could have produced the 2.5-3.5 m thick loam intermediary deposit of the terrace mass. Such event could have occurred in the late Holocene period, thus ca. 4000-2000 BP. We based our writing on earlier observations made by Gratzer and Rai in 1997 (in: Bhutan Soil Survey Project 1998:10). It is not yet clear whether the loam deposits are due to such a process or if it is necessary to look for another explanation. In our opinion, at least the recent time setting seems too late. In our opinion, the loam deposit has rather a colluvial origin with progressive pedologic transformation of its upper interface.

Vegetation Cover

The local vegetation cover consists mainly in blue pine forest (Pinus Wallichiana), which is locally exploited for timber and fuel wood. The ground vegetation in the dense forest is sparse and mostly concentrated in widely forested area (young pines, rose (Rosa sericea), and poplar (Populus). Bamboo (Yushania sp.) grows densely in wet zones and sedges (Juncus sp.) on fringes with irregular drainage (Bhutan Soil Survey Project 1998:13).

The flat terrace areas were mostly deforested. Exotic forage species (Cockfoot grass, perennial ryegrass, and legume white clover) were planted in these locations to improve pasture (Ibid.).

Toponymy

The toponym Batpalathang is a popular derivative of a Tibetan denomination (Boeplagthang) meaning “the place where the Tibetan were defeated”. This transliteration is apparently widespread among the local population. In fact, the geographical data indicates that the name is in fact associated with the nearby locality where the shop signs are indeed mentioning the name Boeplagthang as the locality name. Although the archaeological site is located at 1.1 kilometer from the hamlet Boeplagthang, we kept Batpalathang as site name since the discovery was made at the location of the new RNR research center, named Batpalathang too.