§0 MTDOLEMISs : KANGRA EARTHQUAKE. 



rocks of the Siwalik and Nahan stages. The main boundary fault 

 separates these from the older slates and limestones of the Mussoorie 

 ridge, just as occurs north of Dharmsala in the Kangra Valley 

 generally, and along the Guma-Drang-Mandi line of country already 

 described. 



Dehra Dun Town. 



Dehra Dun, besides being a large native town and the cold weather 

 head-quarters of the district civil staff, has also several battalions of 

 Gurkhas in cantonments. It is also the head-quarters of the Trigono- 

 metrical and Forest Surveys of India, of the Agricultural Chemist and 

 Cryptogamic Botanist to the Government, and of the Forest School. 

 The Imperial Cadet Corps, and the Viceroy's Body-Guard and private 

 stables are also accommodated here. It is consequently a town of 

 considerable size, importance and variety as regards buildings. 



The following notes are by Mr. R. R. Simpson : — 



Dehra Dun is buiit on alluvial sand and boulders, the foundations of 

 Construction of buildings being usually composed of a layer of from 

 buildings, etc. i to 4 ft. of concrete. The buildings are con- 



structed of burnt brick with lime mortar, of boulder masonry with lime 

 mortar, of unburnt brick with mud moitar, or of combinations 

 of these materials. Of these classes the first three are mentioned in 

 order of merit as re sisters of damage due to the recent earthquaking. 

 The value of the !a&t group naturally varies with the kind of 

 combination. With regard to roofing the following different types * in 

 use (pi. 20), are mentioned in order of merit solely with reference to 

 the assistance which they render to the w alls on which they rest (1) 

 arched roof with iron ties ; (2) jack-arched roofing, i.e., composite 

 arches with steel joists, the last arch on either side being tied to the 

 walls ; (3) flat terraced roofs, usually with wooden beams ; (4) pent 

 roofing of galvanized iron on fight, wooden framing ; (5) thatched 

 roofing. 



l Sketches of these types figs. 1, 2 and 3 with explanation were kindly furnished 

 by Captain A. Anderson, Executive Engineer, Public Works Department. 



