According to Kennedy: "Three angular unconformities within the Merced and overlying Colma Formations have formed on the steeply dipping fold forelimb".
The Serra Fault is a low angle imbricate fault that has thrust older Franciscan Assemblage rocks and soils of the Merced Formation over the younger Colma Formation.
[3] The Serra Fault is, therefore, not zoned for Special Studies by the State of California and is classified as Quaternary in age: that is, fault displacement within the past two million years.
Age constraints for coastal exposures of the Pleistocene Colma and uppermost Merced Formations have prior to 2005 been primarily correlative, generating uncertainty about the depositional history of these units as well as the timing of fault activity responsible for lifting them to elevations up to seventy meters along the northwestern coast of the San Francisco Peninsula.
Yi notes that: "Recent studies have suggested that Merced and Colma deposits, as well as younger Holocene inset channel deposits, show fault-propagation fold growth and tilting" related to activity on the Serra Fault itself.