İn Armutlu Peninsula, It has been exposed that rock types representing different times from the Paleozoic to the present. Pamukova metamorphics that is thought to be the Precambrian-Lower Paleozoic age consisting of amphibolit, amphibolit shist, granite, and metavolcanics creats the bases of the region. Lower
Triassic age
Taşköprü formation (siltstone, sandstone), Upper Cretaceous age
Bakacak formation (conglomerate, sandstone),Upper Paleocene-Middle Eocene age
İncebel formation (sandstone, conglomerate, marl), Eocene age Sarısu formation
(conglomerate, mudstone, sandstone, limestone) that covers the basis of sedimentary and volcanosedimantary units. Fıstıklı Granitoid was deposited in the area during the Eocene
. İt is above the old Sarmatian age Kılıç formation (claystone, siltstone, marl), Upper Miocene-Lower Pliocene age Yalakdere formation (sandstone, conglomerate, siltstone, claystone and mudstone) and in the Pleistocene marine terrace deposits and recent alluvial deposits are located.
Quaternary age units in the two delta region and coastal plains are located in the area, with marine sediments deposited in coastal and river environments, consist of sedimantery communities.Exept terrace deposits, Holocene age units,are deposited in sea, sea-river at the shore; and in the land at the stream media, composed of unconsolidated material. These sediments, that are found unconformably on the older aged rock groups, are in transition with each other laterally and vertically. Sea originated units are composed of beach, coastal plane and marsh sediments along the shore.
The most important structural element in neotectonics age is North Anatolian
Fault (KAF). Thin fault in divided into two branches in Armutlu Peninsula as North and South. North arm, following İzmit-Adapazarı corridor, reaches Sea of Marmara.
İn Yalova province, roughly in E-W direction, it continues by following Sea of
Marmara depressions to westward.The other faults in Yalova related to the
Neotectonic period, are in NW-SE and NE-SW directions.The active faults that are monitored in Hersek and Laledere Deltas are located in KAF. These faults produce severe earthquakes from time to time.