Stalagmite growth perturbations from the Kumaun Himalaya as potential earthquake recorders

The central part of the Himalaya (Kumaun and Garhwal Provinces of India) is noted for its prolonged seismic quiescence, and therefore, developing a longer-term time series of past earthquakes to understand their recurrence pattern in this segment assumes importance. In addition to direct observations of offsets in stratigraphic exposures or other proxies like paleoliquefaction, deformation preserved within stalagmites (speleothems) in karst system can be analyzed to obtain continuous millennial scale time series of earthquakes. The Central Indian Himalaya hosts natural caves between major active thrusts forming potential storehouses for paleoseismological records. Here, we present results from the limestone caves in the Kumaun Himalaya and discuss the implications of growth perturbations identified in the stalagmites as possible earthquake recorders. This article focuses on three stalagmites from the Dharamjali Cave located in the eastern Kumaun Himalaya, although two other caves, one of them located in the foothills, were also examined for their suitability. The growth anomalies in stalagmites include abrupt tilting or rotation of growth axes, growth termination, and breakage followed by regrowth. The U-Th age data from three specimens allow us to constrain the intervals of growth anomalies, and these were dated at 4273 +/- 410 years BP (2673-1853 BC), 2782 +/- 79 years BP (851-693 BC), 2498 +/- 117 years BP (605-371 BC), 1503 +/- 245 years BP (262-752 AD), 1346 +/- 101 years BP (563-765 AD), and 687 +/- 147 years BP (1176-1470 AD). The dates may correspond to the timings of major/great earthquakes in the region and the youngest event (1176-1470 AD) shows chronological correspondence with either one of the great medieval earthquakes (1050-1250 and 1259-1433 AD) evident from trench excavations across the Himalayan Frontal Thrust.

Molecular phylogeny of Glyphochloa (Poaceae, Panicoideae), an endemic grass genus from the Western Ghats, India

The genus Glyphochloa (Poaceae: Panicoideae: Andropogoneae: Rottboellinae) is endemic to peninsular India and is distributed on lateritic plateaus of low and high altitude in and around Western Ghats and the Malabar Coast. The genus presumably originated and diversified in the Western Ghats. Species relationships in the genus Glyphochloa were deduced here based on molecular phylogenies inferred using nuclear ribosomal ITS sequences and plastid intergenic spacer regions (atpB-rbcL, trnT-trnL, trnL-trnF), and new observations were made of spikelet morphology, caryopsis morphology and meiotic chromosome counts. We observed two distinct clades of Glyphochloa s.l. One of these (group I') includes Ophiuros bombaiensis, and is characterized by a single-awned lower glume and a base chromosome number of 6; it grows in low elevation coastal areas. The other clade (group II') has a double-awned lower glume, a base chromosome number of 7, and is restricted to higher elevation lateritic plateaus; G. ratnagirica may belong to the group II clade, or may be a third distinct lineage in the genus. A sister-group relationship between group I and II taxa (with or without G. ratnagirica) is not well supported, although the genus is recovered as monophyletic in shortest trees inferred using ITS or concatenated plastid data. We present a key to species of Glyphochloa and make a new combination for O. bombaiensis.