Signatures of the hiatus in star formation unveiled by APOGEE DR17 red giant stars. Density distribution of the observed [α/Fe] vs. [Fe/H] (left panels) and [Fe/α] vs. [α/H] (right panels) abundance ratios (see text for data selection details), where α = Mg (first row), α = Si (second row), and α = O (last row) are reported. On the sides of each panel, the normalised kernel density estimation (KDE) calculated with a Gaussian kernel of the abundance ratio distributions is also reported. The coordinates of the densest regions for the high-α and low-α stars are pinpointed with red and blue lines, respectively. In the right panels, the shaded pink area spans the region of the quantity, Δ[α/H]_peak, defined in Eq. (1). The contour density lines correspond to the number of stars within bins in the specified abundance spaces, while the colour-coding is presented on a logarithmic scale.