The rock strata (sandstone
and limestone) of which the walls consist present every appearance of
having been violently upturned by a huge body penetrating the earth
like a cannon-ball. The general aspect of the crater strikingly
resembles the impression made by a steel projectile shot into an
armor-plate. Mr Tilghman has estimated that a meteorite about five
hundred feet in diameter and moving with a velocity of about five
miles per second would have made just such a perforation upon striking
rocks of the character of those found at this place. There was some
fusion of the colliding masses, and the heat produced some steam from
the small amount of water in the rocks. As a result there has been
found at depth a considerable amount of fused quartz (original
sandstone), and with it innumerable particles or sparks of fused
nickel-iron (original meteorite). A projectile of that size
penetrating eleven to twelve hundred feet into the rocky shell of the
globe must have produced a shock which was perceptible several hundred
miles away.
The great velocity ascribed to the supposed meteorite at the moment of
striking could be accounted for by the fact that it probably plunged
nearly vertically downward, for it formed a circular crater in the
rocky crust of the earth. In that case it would have been less
retarded by the resistance of the atmosphere than are meteorites which
enter the air at a lower angle and shoot ahead hundreds of miles until
friction has nearly destroyed their original motion when they drop
upon the earth.
Pages:
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186