The Zagaje Formation is particularly visible in the
Sołtyków region and is made mostly of Early Jurassic continental mudstone-sandstone deposits linked to the onset of "depositional sequence I". Its age is confirmed as mostly Early
Hettangian through stratigraphic and paleontological analyses, including fossil flora and conchostraca findings. Sedimentological studies divide the Sołtyków profile into three parts: ephemeral reservoir deposits, floodplain and lacustrine sediments, and river channel deposits, highlighting dynamic depositional environments influenced by tectonic subsidence and varying hydrological conditions. Climate wise, the area was located back in the Hettangian around 45°N paleolatitude in
Laurasia within a rise of 5–10°C above present, where it experienced significant climatic and environmental change related with sea-level fluctuations, manifested locally with a notorious retrogradational fluvial-lacustrine sedimentation, with evidence of a humid climate interspersed with drier seasons. Some plant fossils like
Hirmeriella mark points of aridity on what was mostly a humid swampy alluvial-lacustrine habitat. The Zagaje Formation's deposits are known from both outcrops and borehole profiles that consist primarily of sandstones, mudstones, and interspersed coal and siderite layers. It represents a stratigraphic gap with the underlying
Upper Triassic formations and is capped by a transgressive contact with the
Skłoby Formation. The paleoenvironment reflects a dynamic alluvial plain shaped predominantly by high-sinuosity stream processes, transitioning from earlier braided and low-sinuosity stream systems. This evolution is attributed to climatic changes, rising base levels, and decreasing geomorphological gradients. Observations, both from exposures and borehole data, highlight the dominance of avulsion processes, with several depositional subsystems identified. Facies with organic remains are diverse:
riverbed biofacies, derived from meandering channels characterized by fining-upward sequences composed of channel lag deposits, point-bar sands, and finer overlying sediments. The high presence of coprolites has allow also to stablish the tropic chain of the local biota, with a clear full ecosystemical substitution of the older Triassic archosaurs by Dinosaurs. == Biota ==