Brèche de repli impactite | Structure d'impact du bassin de Steinheim | 77,2 grammes de tranche | Ries, Allemagne

This is a fantastic Impactite Fallback Breccia from Germany weighing 77.2 grams and measuring 79x66x11mm. Although not a meteorite, impactites and shatter cones are directly linked to them and their impacts. The Steinheim Basin today exhibits a distinct morphological depression that is ∼110 m deep and ∼3.5 km in diameter; the height of the central uplift totals to more than 140 m. The original size of the pristine crater is estimated to be ∼3.8 km with an original depth of ∼205 m.

As this drainless morphological depression was filled by lake sediments shortly after the impact, the primary crater morphology is widely preserved. The crater rim is formed by steeply inclined and intensely brecciated Upper Jurassic limestone blocks that also contain numerous shattered chert nodules, as well as some loose blocks of the host limestone. An impact breccia, referred to as the so-called ”Primäre Beckenbrekzie” (“primary basin breccia”) and interpreted as a “fallback breccia”, is known from many drillings in the Steinheim Basin.

Mainly composed of Middle to Upper Jurassic limestones, marls, mudstones, and sandstones, the impact breccia inside the morphological depression of the Steinheim Basin is overlain by lake sediments and is obviously preserved in its original thickness and position.   This piece displays very well and is a very nice size showing multiple characteristics of its origin. Would make a beautiful addition to any collection.