Ernstson et al. (2001) interpreted pitted and fractured quartzite cobbles of Lower Triassic conglomerates as new evidence in support of the existence of two large impact structures in the Iberian chain: Azuara and Rubielos de la Cérida (Fig. 1). In this discussion we disagree with their interpretation, and we support a tectonic origin for these deformed quartzite pebbles.

The Azuara structure was interpreted as a probable impact structure (Ernstson et al., 1985). A strong debate about its origin arose some years ago and is still inconclusive. Two hypotheses about its origin are considered plausible: extraterrestrial impact...

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