C. U. Shepard — Meteorite from Mexico. 105 



layers of beach-made rock underlying true reef rock ; and also, 

 if over 120 feet in height, to ascertain directly the character of 

 the rock below this level. 



The elevated atoll, Metia, seventy-five miles northeast of 

 Tahiti, whose maximum height (according to the measurement 

 of officers of the Wilkes Expedition) is 250 feet, I have 

 described as consisting of the true coral-reef rock. My exam- 

 inations were made on the west side where it presents a nearly 

 vertical front to the water. The white compact limestone was, 

 in some parts, almost destitute of fossils, or had only an occa- 

 sional mould of a shell or fragment of coral ;* and in others, it 

 was a fine or coarse coral breccia. My notes written out at the 

 island include the statement that "large masses of corals make 

 some lower layers." This observation, though not as complete 

 as I now see that it should have been, favors the conclusion 

 that the thickness of the reef rock is at least twice as great as 

 the depth to which reef -corals grow, in which case the elevated 

 reef is proof of a subsidence of 120 feet or more. 



The island is so near the route to Tahiti that the doubt which 

 remains could be readily removed. 



20. The subsidence indicated, according to the Darwinian 

 theory, by atolls and barrier reefs was actual, not apparent sub- 

 sidence attributable to change of water-level. The difference 

 in its amount between the Central-Pacific area of subsidence 

 and its limits (§§ 10, 11, above), the gradation or variation in 

 amount of subsidence along chains of islands (§§ 10, 12, 13), and 

 the local character of elevations, like those of Metia, Mangaia 

 and many others, are proofs on this point. 



The preceding explanations have prepared the way for the 

 consideration of the arguments urged against the Darwinian 

 theory, to which I now pass. 



[To be continued.] 



Art. XIII. — On the Meteorite of Fomatldn, Jalisco, Mexico; by 

 Charles Upham Shepard. 



For my knowledge of the Formatlan meteorite I am indebted 

 to Mr. Carlos F. De Landero, Engineer, of Guadalajara, Mex- 

 ico. Along with a fragment weighing 142 grams came his 

 letter of March 11th, stating that it formed portion of a 



* It was this compact rock, white, flint-like in fracture, clinking under the 

 hammer, that was found on analysis by B. Silliman to contain SB - *)? per cent of 

 magnesium carbonate. 



Air. Jocr. Sci. — Third Series, Vol. XXX, No. 176. — August, 1885. 

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