An overall illustration of geology of Istria.
The white part is the southern wedge of Istria, a part of Adria-Apulia tectonic unit. It is thrusting towards the north-east (black arrow) and rotating in the counter clockwise direction. As the result of this process, the mountain chains of External Dinaric Alps (grey and striped) are very much bent. Učka mountain chain, for example is running today in the north-south direction, instead of the typical Dinaric northwest-southeast. The other effect of thrusting Istria wedge are many thrust faults on the border of the process. The major one is the Kvarner thrust fault, separating big Adriatic islands from Istria. But along the line Trieste-Rijeka, in the zone, where Istria is underthrusting below Dinarides, there are several roughly parallel faults, where a few 10 meters high walls can be observed.
Source: L. Placer, M. Vrabec, B. Celarc: The bases for understanding of the NW Dinarides and Istria Peninsula tectonics. GEOLOGIJA,53/1, 55-86, Ljubljana, 2010.