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The highest elevation in the municipality is found in Mount Kalawitan, barangay Bayyo with an Elevation of 2,714 meters above sea level (masl) located at the southern part of the municipality while the lowest is in barangay Tocucan with an elevation of 800 meter above sea level (masl) where all major rivers and creeks drain northeastward. This means that the municipality is ensconced by mountains with natural exit point in the lowest northeastern part (See Elevation Map).


The slope gradients in the municipality were interpreted from topographic maps based on horizontal distances among contour lines. These as follows:

8% nearly level to undulating

8-18% undulating to moderately sloping

18-30% moderately sloping to strongly sloping

Above 30% Steep to very steep

The majority of the total land mass of Bontoc ranges from 18% to 39% which comprises 88.89 percent of the total land area. Moderately sloping to strongly sloping areas are found in almost all the barangays especially in settlement areas. The concentration of serve slopes is found in barangays Mainit, Bayyo, Gonogon, Alab Oriente, Caneo and Tocucan. See Slope Map Figure:

Rock Formation

The surface area of Bontoc is underlain by two rock formation: sedimentary and Igneous….

Land Forms

There are alluvium plain found in central Bontoc and volcanic mountains found in all barangays except Poblacion and Caluttit.


Soil Classification by Physiography

The soils in Bontoc are of sandstone, shale and karstic limestone origin. The depths and horizons differ according to elevation and slope. This means that the soils can be classified by river terraces, minor stream valley, sedimentary hills and mountains, meta sediment and meta volcanic mountain, limestone and volcanic mountain. This soil pattern is presented in Figure ___ and in table 2.2. 

High Lime Stone Mountain

This soil grouping is manifested in terraced side slopes which are distributed in 10 barangays with the high distribution rate found in Mainit with 2,311 hectares.  Tocucan has 451 hectares of this type of soil and Maligcong with 421 hectares.  Total land area of terraced side slopes under this classification is 3,819 hectares. 

High Sedimentary Mountains      

The soil grouping totals 7,900 hectares with 1,307 hectares located in 7 barangays with the biggest concentration found in Guina-ang with 623 hectares and Bayyo with 411 hectares.  It is also concentrated in moderately steep slopes  above 1000 meters above sea level in the barangays of Bayyo (2,778 has), Can-eo (1,615 has), and Bontoc Ili (660 has).  This soil type is also located in the steep slopes of Guina-ang (1,161 has), Maligcong (121 has) and the rest distributed in Mainit, Poblacion, Samoki and Tocucan.

High Volcanic Mountains

This is found in terraced side slopes and steep slopes with the greatest concentration found in Talubin (5,256 has), Talubin (1,312 has) and Maligcong (223 has).

Table 2.2.Soil Distribution by Physiographic Classification per Barangay in Bontoc, 2008


Physiographic Class

Terrain Description



River terrace

Highland river terrace



Minor Stream Valley

Minor stream valley



High Limestone Mountain

Terraced side slopes




Steep slopes



High Metavolcanic and Metasediment Mountains

Terraced side slopes




Steep slopes



High Sedimentary Mountains

Terraced side slopes



(>1000 masl sandstone and shale)

Moderately steep slopes




Steep slopes



High Volcanic Mountain

Terraced side slopes




Steep slopes

Source: Planimetric measurement based from Physiographic Soil Map. Municipal Book of Maps of

Bontoc. July 2008.

Soil Series

There are three type of soils found in Bontoc. These are the Sabangan Clay Loam, Natonin Silt, and several undifferentiated mountain soils.   Sabangan Clay Loam is found in western and southern barangays of Gonogon, Balili, Alab Oriente, Alab Proper, Dalican, Bontoc Ili, Talubin and Bayyo, including the river valley of Chico along Poblacion, Caluttit, and Tocucan. Natonin Silt is prominent in the eastern barangays of Tocucan, Caneo, Talubin and Bayyo, including portions of Bontoc Ili. Undifferentiated mountain soils are left unexplored in barangays Maligcong, Mainit, Dalican, Bontoc Ili, Tocucan, Caneo, Talubin, and Bayyo.