21. I think that we need data from the ground to confirm that these are impact structures , 22. The vitrophyres are dominantly glassy rocks that represent impact melt sheets that fill large impact structures . 23. "' Saarij�rvi "'is an impact structure mostly covered by a small lake by the same name. 24. This lake, which lies in a basalt impact structure , is both saline and alkaline in nature. 25. Stishovite, however, is only known from impact structures . 26. To the southwest of Schiller is the Schiller-Zucchius Basin, a Pre-Nectarian basin ( multi-ringed impact structure ). 27. To the northeast of Zucchius is the Schiller-Zucchius Basin, a Pre-Nectarian basin ( multi-ringed impact structure ). 28. The discovery was made in 1989 and therefore Iso-Naakkima is the fourth known impact structure in Finland. 29. They also noted that evidence for the Kebira Crater being an impact structure lacked direct field observations. 30. The current publications do not list a more precise location for the impact structure than the island.
