The main aim of this study is to determine the tectonicgeomorphologic features of Gençali Fault developed under the control ofyoung tectonic movements. In accordance with this aim, the tectonicmovements and abrasion factors and processes of effectiveness levelemerging throughout geological history were investigated inconsideration of present literature and field studies. In this study, thegeneral physical geographic features of the field where Gençali Faultgoes past were determined primarily, following a differentiation of neotectonicunits in the region through the analysis of lithological andtectonic features by means of 1/25 000 scaled geological and activefault maps, and their relation with new fault lines were asserted. Thestudy includes the evaluation of how mountainous terrains rise anddisintegrate, the age and activeness of the fault, the effect of fault linesin the formation of plains, the formation of the river systems, theirimprovements and effects on the field, how deltas are formed, thedetermination of erosion surface and their dispersion in the field, andthe ageing of the field in terms of cycles.The main morphologic expression of the field was shaped incontrol of the tectonic activity. This field, where genetically fluvialconditions are effective, is shaped virtually by internal dynamics.Especially the neo-tectonic period and its cratonic feature caused tofraction and faulting, thus the image of faulted structure emerged.In this study, ArcGIS 10.2 programme and CBS were used fordata input and analysis, and location, geology, relief, slope, exposure,topography, fault and earthquake maps were drawn accordingly. Thegeomorphology map of the studied field was drawn via Adobe PhotoshopCS3 Portable. The obtained data was evaluated through field studies atdifferent dates in 2014 and in the meantime, the photos of the fieldwere taken both aerial and overland.In many fieldwork, it is possible to discover the trace of the periodof neotectonic on the landforms. As well as being the trace of the formsof neotectonic formed at paleotectonic period, those landforms either776 Halid PEKTEZELTurkish StudiesInternational Periodical For the Languages, Literature and History of Turkish or TurkicVolume 10/2 Winter 2015are formed with the movement that has started in the middle of mioceneor covered and eroded due to the effect of denudational process. Theraare also evidence that shows tectonic movements accured inpaleotectonic period. However, they almost lost their direct effect onlandforms that we observe today.Vertical and strike slip faults, fault slopes, fault steps, tectonicslopes, fault lines, linelike dales, antecedant bospourus, tectonic downs,offset streams, linear backs, river gazebos, facets in fieldwork areoccured with neotectonic movements and the process of fluvialis.Because of those neotectonic movements paleotectonic surfaces rise atsome places (Gürle Mounts), warp or cause lowlands (EngürücükLowland) through breaking down. Forms that occured with tectonicmovements and the process of fluvialis are shown on the map ofgoemorphology.Gençali Faults existing in Marmara region is a small part of NorthAnatolia Fault (KAFZ) Zone. This fault line takes its form under theinfluence of D – B oriented jam, K – G oriented strain and ground toground boarden regime with the effect of KAFZ. Structurel formsconnected to tectonic fault constitute the main relief in fieldwork.Topography shaped by young faulting with the end of pliocence andpost pliocence tectonic movement is at the stage of advance youth. Thebody of river and its development are associated with stated fault or itssegments. Connected to poleotectonic and post poleotectonic movement,young fault blockeds and tectonic warps cause decay of river drainageand ruins the development of dale.Gençali Fault occurred as a result of tectonic movements at theend of Pliocene period. This fault has shifted Koca River and its mostimportant branch Kurtul River by cutting them horizontally where theyrun north-wards (to Gemlik Bay) and changed their base. Both rivershave adapted to this tectonic elevation easily and sank to their terrain,creating typical antecedent straits (Kurtul and Muratoba). The elevationof the field as a result of tectonic movements at the end of Plioceneperiod and negative changes in the eustatic bottom level in earlyPleistocene period caused the rivers to sink into their beds by causinghead erosion and also caused typical bedrock terrace sets alongprinciple valleys.There is not a possible dip-slip fault in the Map of Active Faults inTurkey which is prepared by Emre et al.(2012) under the supervision ofGeneral Dictatorate of Mineral Research and Exploration (we namedthis fault as Engücürük in our study). We think this fault should beplaced in the Map of Active Faults in Turkey considering its locationand geomorphologic qualities.Gençali Fault has a significant vertical-slip fault as well as being aright-lateral strike-slip fault. This fault has elevated the south blockand lowered the north block. It led to the emergence of İznik basin ofGençali Fault and Gemlik Bay along with Gemlik Fault Zone. Likewise,Engürücük Plain was formed as a result of tectonic subsidence whichoccurred because of Umurbey Fault in the North, a possible EngürücükFault in the East and Gençali Fault in the South.Gençali Fayı’nın (Bursa) Tektonik Jeomorfoloji Özellikler 777Turkish StudiesInternational Periodical For the Languages, Literature and History of Turkish or TurkicVolume 10/2 Winter 2015The fact that earthquakes occur frequently around the study fieldis the evidence that Gençali Fault is still an active fault today and thatthe tectonic activity is still happening. As a result, while making newtown planning and housing plans in the study field, this tectonicactivity and