Show science seeks clue chic to misplaced 9 vein of volcanic lava BOULDER DAM COLO ten miles south of this massive concrete structure geologists have discovered a missing link in volcanic history a lava dike formed in gravel ho how w it got there is the problem worry worrying ing prof lan ian campbell of the california institute of technology and dr E T schenk of the national park service who have decided the dike is a mire mere geological youngster of some years never before has lava been found cutting through gravel and how it forced its way into a porous rock of this type in such clean cut fashion is a big mystery it is difficult to believe the geologists have reported that an open faur tour four feet wide could have b been en ahrmed f formed or maintained in these gravels while the dike magma was pouring in from below A possible explanation may be that the first surge of lava was rapidly chilled by contact with the cold and perhaps water filled gravel this chilled glass glans thenceforward formed a seal which prevented any side is escape as the remaining bulkot bulk of the magma pushed in S spectacular too Is the texture of the dike itself most dikes that are intruded into the shallower parts of the earths crust are very fine grained |