Using data from the GALAH pilot survey , we determine properties of the Galactic thin and thick disks near the solar neighbourhood . The data cover a small range of Galactocentric radius ( 7.9 \la R _ { \mathrm { GC } } \la 9.5 kpc ) , but extend up to 4 kpc in height from the Galactic plane , and several kpc in the direction of Galactic anti-rotation ( at longitude 260 ^ { \circ } \leq \ell \leq 280 ^ { \circ } ) . This allows us to reliably measure the vertical density and abundance profiles of the chemically and kinematically defined ‘ thick ’ and ‘ thin ’ disks of the Galaxy . The thin disk ( low- \alpha population ) exhibits a steep negative vertical metallicity gradient , at d [ M/H ] /d z = -0.18 \pm 0.01 dex kpc ^ { -1 } , which is broadly consistent with previous studies . In contrast , its vertical \alpha -abundance profile is almost flat , with a gradient of d [ \alpha /M ] /d z = 0.008 \pm 0.002 dex kpc ^ { -1 } . The steep vertical metallicity gradient of the low- \alpha population is in agreement with models where radial migration has a major role in the evolution of the thin disk . The thick disk ( high- \alpha population ) has a weaker vertical metallicity gradient d [ M/H ] /d z = -0.058 \pm 0.003 dex kpc ^ { -1 } . The \alpha -abundance of the thick disk is nearly constant with height , d [ \alpha /M ] /d z = 0.007 \pm 0.002 dex kpc ^ { -1 } . The negative gradient in metallicity and the small gradient in [ \alpha /M ] indicate that the high- \alpha population experienced a settling phase , but also formed prior to the onset of major SNIa enrichment . We explore the implications of the distinct \alpha -enrichments and narrow [ \alpha /M ] range of the sub-populations in the context of thick disk formation .