1892.] ~ Geology and Paleontology. 693 
General Notes. 
GEOLOGY AND PALEONTOLOGY. 
The Mexican Meteorites.—Geologists are indebted to Mr. J. 
R. Eastman for a concise account of the Mexican meteorites. In a 
paper read before the Philosophical Society of Washington Jan. 2, 
1892, he presented the latest and most complete information upon the 
subject, in a compact form convenient for reference. A list of the 
iron meteorites, with a table of their weights was given, followed by 
remarks as to the relative occurrence of iron and stony meteorites. 
From the available data the ratio of weight of the former to the 
latter is as 1 to 12.23. The aggregate weight of meteoric iron observed 
and discovered to date on this continent is about 153 tons. If the 
above ratio is true in all cases there should have been a fall of about 
1,880 tons of stony meteorites, or in all over 2,000 tons of meteoric 
matter precipitated upon the earth. 
Mr. Eastman offers the following theory to account for the apparent 
excess of iron over stony meteorites: When a stony meteorite falls to 
the earth it generally breaks into many fragments, and the ruptured 
surfaces plainly indicate the nature of the catastrophe. The author 
knew of no case where an iron meteorite showed any indication of 
having been twisted, broken, or torn off from another mass of the 
same material. 
The true type of meteorite which reaches the earth from outer space 
is probably like that which fell in Iowa county, Iowa, on Feb. 12, 
1875. This meteorite is composed almost wholly of stony matter, but 
scattered through the mass are small grains of nickeliferous iron. This 
iron may exist in the stony matrix in all forms and sizes, from the 
microscopic nodule to the mass weighing several tons. When the stony 
mass comes in contact with the earth’s atmosphere the impact breaks 
up the matrix, sets free the iron bodies and they reach the earth in the 
same condition, so far as mass and figure are concerned, as they exist 
in the original formation. In such cases it is probable that the stony 
portion of the original body is rent into such minute fragments by the 
explosion, that they would not reach the earth in any appreciable size. 
The larger the masses of iron the more complete would be the destruc- 
tion of the original body, and the larger stony meteorites would be 
