Geology Regional of Pangandaran

Fauna found in the Pananjung Nature Reserve

Fauna found in the Pananjung Nature Reserve

Seen from the geological map of Pangandaran and surrounding area, this area has 6 formations rock namely jampang formation, pamutuan formation, kalkarenit member of pamutuan formation, tuff memnum formation pamutuan members, kalipucang formation, and alluvial.

Geology regional map of Pangandaran and surrounding area

Geology regional map of Pangandaran and surrounding area

Jampang Formation (Tomj) was composed of volcanic rocks that material in the form of breccia, tuff, and insertion of this rock lava berselingan with sandstones, claystone and napal with conglomerate inserts, sandstone and diamictid sandstone. The Pamutuan Formation (Tmpa) is based on regional data composed by, among others, sandstone, napal, tuff, calcarenite, claystone and limestone. Kalkarenit member of Formation Pamutuan (Tmpl) was composed by Kalkarenit and limestone clastic interspersed with napal. Tuf Napalan member of Pamutuan Formation (Tmpt) are composed by adjoining napal tuffs with inner sandstone, claystone and limestone. Kalipucang Formation (Tmkl) is a limestone reef. Alluvial is a unit of rock that processing sedimentation, there are the formation of sediment, weathering, transportation formed from the previous rock.

Geoturism

Pangandaran has two places that will be geosite, there are Bojong waterfall and cave, then it has two places as geosite namely Pangandaran Beach and Nature Reserve.

spot location map visit

spot location map visit

a. Bojong Waterfall

Bojong waterfall was located in ciputrapinggan river at coordinates E 1080 40’ 43,3” and S 70 38’ 46” (station 9). This waterfall has a height of about 5.5 m and composed by volcanic breccia unit of jampang formation, with monomic components of andesite. Generally, it does not show beddings, the exposed breccia have tuff as matrix, fresh colors is whitish-gray, and weathered colors is blackish-gray, hardness, vesicular, medium-course grains, medium sorting, grain supported, it has quartz minerals, biotite, and feldspar. This volcanic breccia unit is an early oligocene-miocene.

panagandaran 1
pangandaran2
pangandaran 3

b. Gua

This cave at coordinates E 1080 40’ 3,7” and S 70 39’ 28,5” (station 7). The cave has a height of about 80 cm and was composed by reef limestone units of the pamutuan formation. This limestone is an autochtonous type with whitish-brown fresh color and light brown weathered color. It was composed by calcite crystals that are pretified by dissolution of limestone by water, where the pretification hole was filled by calcite crystals.

gua pangandaran
gua pangandaran 2

c. Pantai Pangandaran

Pangandaran is largely controlled by fluvial processes, fluvio marine and marine, so the coastal area have almost diverse typologies. Coastal typology belonging to the Pangandaran coastal area that is marine diposition coast, coast bulid by organism, and wave erosion coast.

Typology of marine deposition coast is a dominant beach typology in the Pangandaran coastal area. This typology located on the west coast and east coast of pangandaran and white sand beach. Typology characterized by the presence of pocket beach which is the accumulation of marine sediment material by currents or waves. Coastal with this typology located in a bay so also called has a pocket beach. The coastal dynamics that occur in this typology is the deposition of marine sediment materials. This material is in the form of coarse sand beach and bioclastic material formed from the residue of the animal or plant. Additionally, pangandaran was a result of marine sediment deposition that make formed and connecting Java island to Panajung island with tombolo form.

white sand beach as marine deposition coast

white sand beach as marine deposition coast

The typology of coast build by organism found in Pangandaran which associated with the typology of marine deposition coast. This beach is adjacent to a white sand beach. This beach has a reeffrom as far as 100 meters toward the sea breaker zone where the depth is less than 2 meters. On this beach there is a stretch of coral reefs that grow quite intensive. The beach with typology like this only formed in one corner of the beach on Pananjung island. Although the area is narrow, but this type of beach typology has been exploited by the local government to spot snorkeling.

Reeffrom overlay as far as 100 m

Reeffrom overlay as far as 100 m

Typology of wave erosion coast found on most of Pananjung island cape in Pangandaran This typology is seen with the characteristics such as the form of beach are winding or steep irregular, beach material dominated sand and marked by the existence of stack in the form of destruction of rocks with various sizes that come from the wall of the beach (cliff). Beach dynamics that occur in this area is erosion by wave (abrasion). However, since the rock composite material in this region is hard limestone, and there are no facilities and infrastructure public that are there so that the abrasion that occurs there is not so risky and feasible.

Steep cliffs erosion ocean waves
Steep cliffs erosion ocean waves

Based on its typology, the Pangandaran Beach has the potential and problems of coastal area, including :

  • Potential for tourism

Each coastal typology has potential for making tourist attractions, considering each beach typology has unique characteristics that deserve to be offered as a site of turism. The wave erosion coast typology has the appearance of a large open sea. In addition, this typology in some places allows for use as a rock climbing arena.

Coastal typology with of marine deposition coast type has a beach whisper that can be used as a place to play, swim, walks, and other activities that can be done during the tour.

The problem that occurred this place was the waste from the tourism activities that pollute the beach. In addition, the characteristics of the pocket-shaped beach and dealing with the high seas, he is very prone to the tsunami waves.

  • Potential for fishery

Pangandaran beach bordering with the sea has potential in the field of fisheries is quite potential. This is evidenced by the presence of a large fish auction in the east coast of Pangandaran.

  • Potential for farms

The most potential farms to be developed in the coastal area of Pangandaran especially in Pananjung island, is the cultivation of swift’s nest. This cultivation has been developed almost in all coastal areas of Pananjung island because there are many cliffs, notch, and sea cave. Nevertheless, the cultivation of swiftlet nest newly done at the beach, that is the cliff overlooking the sea.

d. Nature Reserve

Pananjung Nature Reserve is a hill covering more than 530 hectares. Geographically the Pananjung Nature Reserve is located at 1080 38’ 50” West longitude – 1080 40’ 38” East longitude and 70 42’ 20” North latitude – 70 43’ 51” South latitude (station 2). The topography of this area starts from small hills to high hills with elevation of 100 sea water level. Seen from its geological condition, this region is composed by reef limestone units of kalipucang formation and breccia unit of formation jampang with polymic components ie limestones and igneous rocks, and sandstone matrix. According to the classification of Schmidt and Ferguson, Pananjung Nature Reserve includes climate type B with average rainfall 3,196 mm per year, air temperature between 80-90%.

Flora which contained approximately 80% is the old secondary forest vegetation and the rest is primary forest. The dominant trees include Laban (Vitex pubescens), Kisegel (Dilenia excelsea), and Marong (Cratoxylon formosum). In addition there are also many types of trees such as Reungas (Buchanania arborencens), Kondang (Ficus variegata), teureup (Artocarpus elsatica) and others. The Baringtonia formation consists of Nyamplung (Callophylum inophylum), Waru sea (Hibiscus tiliaceus), Ketapang (Terminalia cattapa), and Butun (Baringtonia aistica). In the lowlands there is a plant forest which is an exotica plant, which consists of teak plants (Tectona grandis), Mahogany (Swietenia mahagoni) and Komis (Acacia auriculirformis).

The wildlife in this area include Bull (Bos sondaicus), Kijang (Muntiacus muntjak), Tando (Cynocephalus variegatus), Bat (Pteroptus vampyrus), Gray monkeys (Macaca fascicularis), Lutung (Trcyphithecus auratus), Kangkareng (Anthracoceros convexus), Hornbills (Buceros rhinoceros), and Forest Chickens (Gallus gallus).

Fauna found in the Pananjung Nature Reserve
Fauna found in the Pananjung Nature Reserve
Fauna found in the Pananjung Nature Reserve
Fauna found in the Pananjung Nature Reserve

Pananjung Nature Reserve can provide some functions to the general public, both for public interest, science, research and education. This area is a natural laboratory, where the process of natural life is not so disturbed. Wildlife, marine biota, and vegetation is very interesting and allows interesting natural tourism activities.

Land Use

RBI maps Pangandaran area (Bakosurtanal sheet 1308-232)

RBI maps Pangandaran area (Bakosurtanal sheet 1308-232)

Land use of Pangandaran and surrounding area is divided into several types of utilization such as settlement area, garden area and rice field, forest area, coastal area, and conservation area. The settlements area (in the figure marked by pink) are mostly scattered near the beaches in the southern part of the research area because the beaches in the study area are a developing tourism area. Besides near the beach, there are also some scattered settlements in the north to northeast which is a hilly area that is covered by a lot of vegetation (in the figure marked by green). In the north-northwest part of the research area which is a hilly area widely used for irrigated rice fields, fields, or plantation areas (in the figure marked by yellow). Coastal areas located in the southern part of the study area where much exploited as tourist area, ports citizens and fishponds. In the southern part (headland) is a research area and there is a conservation area or a nature reserve that is protected forest and has steep cliffs.

 

Potensi Bencana

The potential of disaster in the Pangandaran area are Tsunami, Earthquake, Flood, and Landslide.

a. Tsunami

Based on the research, Potential tsunami Pangandaran on the highest position compared to tsunami potential in other coastal areas in West Java. Based on the history of the largest tsunami disaster that ever occurred in the area of Pangandaran occurred on July 16th, 2006. Disaster that happened at the time it can not be predicted accurately if seen the history and study of experts. But in geology there is the term paleotsunami. Paleotsunami is an ancient tsunami or tsunami that occurred in old time. Paleotsunami research is a study to find out tsunami that have occurred in the past based on geological evidence. The evidence is generally in the form of tsunami sand deposits.

The tsunami sand deposits have distinctive features that can be distinguished from other sand deposits. These deposits are often found to cover the old soil layer. Generally, the tsunami sand deposits show the appearance of the structure of grain size fining upward gradually. In one tsunami deposit, this structure can be seen more than one. This structure is a clue to many waves that struck when the tsunami occurred.

The results of paleotsunami research can also be used as a reference in the preparation of spatial coastal areas that observe the potential of tsunami disaster. This is done by understanding the distribution of ancient tsunami deposits. Generally, pangandaran beach prone to tsunami disaster. This is happen because the two regions are both in earthquake prone zones as a result of subduction between the Indo-Australian ocean plate and the Eurasian continental plate. The interaction of the two plates continues from the first to the present and in the future. Thus, earthquakes can still occur again at any time, as well as tsunami.

The first deposition which is located at a depth of 10-20 cm from the surface was predicted to be a tsunami deposit on 1921. The thickness of this deposit reaches up to 4 cm. For comparison on July 2006, the thickness sand deposit of tsunami in the Pangandaran area reaches up to 11 cm. Besides its thickness, the tsunami deposit are very similar to the tsunami sediment in July 2006 that consists of only one layer of black sand. This sand resembles the sand beaches in the area Pangandaran. The grain size of the sand is well sorted from bottom to top and contains quartz, iron ore, and sand-shell fragments. This layer can not be found in every possible place because some has been lost eroded erosion after precipitation.

The second tsunami sediment layer is at a depth of 2 m below the surface. The thickness of this layer reaches up to 15 cm, black slightly brown color. In the sand contains soil chunks. These chunks are probably the result of scouring by tsunami waves which are then deposited with the sand they carry. This layer although quite thick, but looks not continuous. What is interesting about this second layer of tsunami sediment is that it is flanked by layers of green clay deposits at the bottom and a layer of brown clay on the top. The boundary of the tsunami sediment layer with both layers of clay is very firm. The green clay at the bottom may be deposited in the lagoon environment, while the brown clay on top of it containing a little sand may be deposited on land.

The environmental change from pre-tsunami lagoons to land after tsunami sand was deposited indicates that the earthquake that occurred at the time besides generated tsunami waves, was also accompanied by lifting of land. This indicates that the earthquake that occurred at that time is likely to be a powerful earthquake.

Tsunami hazard risk map of Pangandaran area

Tsunami hazard risk map of Pangandaran area

b. Flood

Flood in Pangandaran making activities and partly paralyzed residents to evacuate. Floods occurred in Pangandaran itself largely caused by:

  • Natural events such as rainfall over long periods.
  • Bad handling of garbage, until then the source of drains clogged.
  • In the area very less water infiltration. So facilitate flood disaster happen.
  • Conditions of land covered with cement, paving or asphalt, so that can’t be infiltrate water.
  • Construction of settlements where vacant land is converted into street of building, parking area, so there’s no infiltration of rain water.
  • Flash floods

The following are some of Pangandaran areas that are flooded disaster:

  • Bojongtempel, Babakan Village

This area is flood subscription, if the flood is large enough then the people be ordered to evacuate to a highest area, many people who fled to friends or siblings who are not affected by floods, floods in this area often reaches to the adult chest even in the north more deeply . One of the people said the water rises even though the rain has stopped, this is probably the water from the mountainous areas in the northern part of Pangandaran.

  • Bojongjati, Pananjung Village

No different with the Babakan Village that is close to the flow of cikidang river make the most of Bojongjati areas flooded.

  • Kandang Menjangan Area

Wilayah ini biasanya tergenang diseluruh bagian jika dilanda hujan, sebuah wilayah kecil ditengah persawahan desa pananjung dan purbahayu yang dihuni puluhan kepala keluarga ini dipastikan tergenang, bahkan jalan yang menghubungkan wilayah pananjung dengan purbahayu lumpuh.

The area is usually flooded in all part if rain, a small area in the middle of paddy field in Pananjung and Purbahayu village which is occupied by dozens head of family is sure to be flooded, even the roads that connect region with Pananjung with Purbahayu paralyzed.

  • Cijoho a, Parigi District

Cijoho was once flash floods causing paralysis of the main route Parigi-Cigugur, people who will going to Cigugur must take an alternative route via Cintaratu to then exit in Cibenda if going to Pangandaran or otherwise. Until this news was sent no casualties fell, although there is one house that almost eroded the flow of water but the residents of the house has been successfully evacuated.

  • Kalipucang

The front area of the Kalipucang market that has become a subscription to floods, heavy rains and overflowing river citanduy make this area continues to be flooded when the rainy season comes.

c. Longsor

In addition to floods, landslide disaster is also common in Pangandaran area. Areas that have occurred landslides are: Langkaplancar District, Padaherang District, and Cijulang District. The average occurrence of this landslide is caused by the occurrence of soil erosion to leave only rocks, and no infiltration water when rainy in area.

Daftar Pustaka

Simanjuntak dan Surono. 1992. Peta Geologi Regional Lembar Pangandaran. Pusat Pengembangan dan Penelitian Geologi.

Peta Bakosurtanal Lembar Pananjung edisi I tahun 1999.

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