DEPARTMENT OF THE INTERIOR,
UNITED STATES GEOLOGICAL SURVEY,
Washington, May 16, 1912.HON. WILLIAM ALDEN SMITH,
Chairman Subcommittee United States Senate, Washington D. C.MY DEAR SIR: Replying to a letter of May 8 requesting information concerning the possibility of the Titanic having had its hull torn open by a mass of rock imbedded in the submerged portion of the iceberg with which it collided:
As Prof. E. H. Williams, Jr., suggests, in his card which you inclose, such may possibly have been the case. It certainly appears that such an ice mass, around with embedded rock fragments, would be much more effective in ripping open the plates of a ship's hull than a mass of clear ice. It is a well-known fact, as reported by numerous Arctic explorers, that some at least of the Greenland icebergs transport rock masses. In one of his addresses delivered in Washington last year, either that before the Geological Society of Washington, or one before the National Academy of Sciences, Sir John Murray referred to the abundant bowlders found by the dredging of the Challenger expedition, scattered over parts of the bottom of the North Atlantic. He referred to these as being so numerous in places that were the sea bottom elevated and drained so as to become land he thought geologists would be inclined to refer the deposit to a continental ice sheet, as has been done with the drift spread over the north half of the North American Continent.
Dr. Elisha Kent Kane, in his volume on the "U. S. Grinnell Expedition," 1854, p. 113, describes bergs covered with detritus or rock fragments, varying in size from mere pebbles to large blocks. He writes of one as follows: "The berg had evidently changed its equilibrium, and it seemed as if these rocks had been cemented in its former base and had there been subjected to attrition during its rotary oscillations against the bottom of the sea."
On page 455 he describes the overturning of bergs due to changes in their equilibrium, and, referring to rock-studded ice, states (p. 456):
"In such cases the deeply embedded position of the larger fragments spoke of their having been there from the original structure of the berg."
Further (p. 457):"Of nearly 5,000 bergs which I have seen there was perhaps not one that did not contain fragmentary rock."
In his Arctic Expeditions: The Second Grinnell Expedition (vol. 2, 1856, pp. 156, 157), Dr. Kane describes ice in Marshall Bay covered with millions of tons of rock debris. Concerning this he writes:
"I have found masses that had been detached in this way floating many miles out to sea - long symmetrical tables, 200 feet long by 80 broad, covered with large angular rocks and bowlders, and seemingly impregnated throughout with detrital matter. These rafts in Marshall Bay were so numerous that could they have melted as I saw them the bottom of the sea would have presented a more curious study for the geologist than the bowlder-covered lines of our middle latitudes."
It should be noted however, that these ice rafts probably do not transport their loads to such low latitudes as are reached by the more massive bergs.
Dr. I. I. Hayes, in his volume on The Open Polar Sea, a narrative of a voyage of discovery toward the North Pole (1867, pp. 403, 404), describes the rock debris dropped upon the ice from cliffs along the shore and thence drifted away. He writes:"The amount of rock thus transported to the ocean is immense, and yet it falls far short of that which is carried by the icebergs, the rock and sand embedded in which, as they lay in the parent glacier, being sometimes sufficient to bear them down under the weight until but the merest fragments rise above the surface. As the berg melts, the rock and sand fall to the bottom of the ocean; and, if the place of their deposit should one day rise above the sea level, some geological students of future ages may, perhaps, be as much puzzled to know how they came there as those of the present generation are to account for the bowlders of the Connecticut Valley."
The amount of rock in any one iceberg is, however, probably small, so that it is not generally noticeable in the bergs which reach the lower latitudes, at least in those parts of the bergs which extend above the water level. Holland (1877), as quoted by James D. Dana (Manual of Geology, Fourth Edition, 1895, p. 252), states that most of the Greenland icebergs are clean, but "now and then one is seen with bowlders upon it, and here and there small bergs that are quite covered with stones and gravel."...
The Greenland glaciers extending from the great ice cap down the valleys which notch the margin of the interior up and, as described by other observers, do not carry a great amount of rock debris, and most of this is embedded in the lower part of the ice. When these glaciers extend into water sufficiently deep for icebergs to break off, most of the debris would thus be in the basal part of the ice and, since but one- ninth of the mass of floating ice extends above the water level, most of the debris in a berg standing 50 to 100 feet above the surface of the sea would at first be far below the depth at which a ship's hull would encounter it. With the melting of the ice as it floats southward, the rock fragments are released and dropped to the sea bottom. The most distant of this glacionatant deposition is said to take place about the banks of Newfoundland, or between meridians 44 and 52 and north of parallel 40' 30'. Some of the rock is probably carried still farther south, especially in such a year as 1912, when the icebergs are reported as having been seen much farther south than is customary. It is thus quite possible that rock masses may have been embedded in the berg which the Titanic encountered. While most of the debris is probably embedded in the basal part of such ice masses, melting of the part of the ice exposed above the water would cause the basal part to be gradually raised toward the surface. Moreover, the tilting of icebergs from their original positions results from the change of the center of gravity, due to disruption and unequal melting of different parts of the mass. Such bergs are also known to turn over, so that even though the upper part of the berg were at first free from rock debris, the rock-shod part might be brought up to a level where a ship's hull would encounter it.
Masses of rock 50 feet or more in circumference are known to have been transported by continental glaciers and it is quite possible that large masses of rock may be carried by some of the icebergs, though probably most of the stones are comparatively small. However, one large rock firmly embedded in the ice at the point of contact would certainly be most effective in ripping open a ship's hull under the force of a glancing impact. Ice in such a great mass as the berg which was encountered is, however, probably quite competent to produce disastrous results experienced without calling for the presence of any included mass of rock.
Very respectfully,
GEO. OTIS SMITH,
Director.