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BKIEF DESCRIPTIONS OF THE KOCKS.
G. HENRY KINAHAN,
ENGINEER DIPLOMATIST, THIN. COLL. DUBLIN; MEMBER OP THE ROYAL IRISH
AWANT expressed by many Geologists and often felt by the Author, is a classified Handy-book Op Rock Names. It is hoped that, until a better appears, this Manual may be useful to the Public.
To write such a work satisfactorily is no easy task. In other branches of Natural Science, such as Botany, Zoology, and the like, some systematic nomenclature has been followed, but in Geology no one system has been used, or all system has been ignored. It is not uncommon to find eminent Petrologists calling the same rock by several names, or, what is more perplexing, using for a rock a name already given to a totally different one. At the present time Rock names are in such confusion that if an observer names a rock, without at the same time mentioning his authority, he may be supposed to be referring to a rock, or even rocks, totally different to that which he intended to illustrate. This irregularity has caused many names to be used, not only unscientifically but also absurdly, as the original name may refer to a mineral or character not possessed by the rock or rocks to which it is now applied. From the above it is evident that a compiler of such a book as this Manual must run contrary to the opinions and
prejudices of many geologists; therefore some will find fault even if the work could be well done.
I would wish to impress on my readers that this book lias been written as a reference for surveyors and students while engaged in the field. Should they desire a perfect knowledge of rocks, they must study the various papers and works of the different eminent Petrologists. The work, necessarily, is far from perfect: still I hope it may be of some small use or help to learners of Geology.
During the compilation of this Manual, the writings of numerous Petrologists have been consulted and quoted; also works on general subjects from which information could be procured. Dana's suggestions as to the termination of Rock names have been adopted as far as practicable, while the older names for rocks are generally adopted, except when they are objectionable or better names have since been proposed. Such local names as were known are also given, as they may assist explorers in gleaning information about a country. To various fellow-labourers I am much indebted: to D. Forbes, F.R.S., &c, for information; also to W. King, Dep. Supt. Geol. Surv., India, and for his valuable assistance while arranging and classifying the rocks. I should also mention the names of the Rev. M. H. Close, M.R.I.A., &c.; Stackpoole Westropp, M.D., M.R.I.A., &c.; and H. Leonard, M.R.I.A.; besides others who have supplied me with lists of local names.