Ground water in the East Portland area, Oregon

Abstract

Major topographic subareas_______________________________ 8 Boring Hills.____________________________________ 9 Kelso slope.__________________________________________ 9 Portland terraces____----_______-_____-___--____--__-_-Oatfield Heights ridge__________________________________ Columbia River flood plain________________________-_.__ Minor flood plains and terraces____________________________ Major streams that border the area__--_-_-_-_--_---__-_____-Small streams that drain the area____________-__________-___-Geology._________________________________________________________ General character and relation of the rock units ___________________ The rock units and their water-bearing character._________________ Older rocks.___-_-___---__--_______-_-___-___-_____-___--_ Columbia River Basalt..___________________________________ Sandy River Mudstone___________________________________ Troutdale Formation_____________________________________ Boring Lava._____________________________________________ Piedmont deposits.________________________________________ Fluviolacustrine deposits_________________________________ Alluvium of an abandoned river channel____________________ Younger terrace deposits-----_____-_________-____________-_-Younger alluvium.________________________________________ Summary of geologic history.___________________________________ Ground water_____________________________________________________ General features of occurrence__________________________________-Water-level fluctuations._______________________________________ Occurrence in the subareas____________________________________ Boring Hills.._____________________________________ Kelso slope.______________________________________________ Portland terraces.