TRANSACTIONS OF SECTION C. i-3 



then expanded by heating, so as to allow the marble to pass completely into it, and 

 leave about 3 centimetres of the tube free at either end. On allowinur the tube to 

 cool a perfect contact between the iron and marble was obtained, and it was no 

 longer possible to withdraw the latter. Any very slight failure to tit at any point, 

 if such a failure existed in any case, was rendered harmless by the fact that under a 

 comparatively low pressure the limestone is found to be sufficiently elastic not only 

 to fill up any such minute space, but even to stretch the tube, and, ou the pressure 

 being relieved, to contract again to its original form, so that it will drop out of 

 the tube which has been thus enlarged. Into either end of the tube containing 

 the small column an accurately fitting sliding steel plug was inserted, and by 

 means of these the marble was submitted to a pressure far above that which would 

 be sufficient to crush it if not so inclosed. The machine employed in obtaining 

 the pressure was so arranged that the pressure might be maintained for weeks, or 

 even months, if required. Under these circumstances the conditions of pressure to 

 which the marble is subjected are those in the ' zone of tiow ' of the earth's 

 crust — those, namely, of a pressure above that of its elastic limit, while 

 yet unable to break in the ordinarj^ manner owing to the tube which confines 

 it having a still higher elastic limit. Under the pressure, which was applied 

 gradually and in some cases continued for several weeks, the tube was found to 

 slowly bulge until a very marked enlargement of the portion surrounding the 

 marble had taken place. The tube was then cut through longitudinally by means 

 of a milling machine along two lines opposite one another. 



The marble within, however, was still firm, and held the respective sides of the 

 iron tube, now completely separated, so tightly together that it was impossible 

 without mechanical aids to tear these apart. By means of a wedge, however, they 

 could be separated, splitting the marble through longitudinally. The column in 

 one experiment was reduced from 40 millimetres to 21 millimetres in height. The 

 deformed marble differs from the original rock in having a dead white colour, the 

 glistening cleavage faces of calcite being no longer visible, and although not so 

 hard as the original rock, it is still firm and compact, and especially so when its 

 delormation has been carried out very slowly. No accurate measurements as to 

 its strength have yet been made, but it will withstand a sharp blow, and fragments 

 of it, weighing 10 grams, have been allowed to fall through a height of over 

 2A metres (8 feet) on to a wooden platform, from which it rebounded without 

 breaking. Thin sections of the deformed marble, when examined under the micro- 

 scope, show that the calcite individuals composing the rock have in many cases 

 been twisted and flattened, and in the majority of cases a very fine polysynthetic 

 pressure-twinning has been induced in them, with movement along gliding planes, 

 as well as several other structures seen in nature in highly deformed rocks. 



The experiments therefore show that limestone, even when dry and at ordinary 

 temperatures, does possess a certain degree of plasticity, and can be made to 

 ' flow,' the movements set up developing many structures which are characteristic 

 of rocks which have been squeezed or folded in the deeper portions of our earth's 

 crust. 



6. The Former Extension of the Appalachians across Mississippi, Louis- 

 iana, and Texas.^ By John C. Bkannee, Ph.D., Professor of Geology, 

 Stanford University. 



I. The Ouachita anticline is the structural equivalent of the Cincinnati- 

 Nashville arch : this fold continues westward through the Arbuckle Mountains in 

 Indian Territory and to the Wichita Mountains in Southern Oklahoma Territory. 



II. The Coal Measures drainage of the Illinois-Indiana-Kentucky basin flowed 

 westward through the Arkansas valley into a Carboniferous mediterranean sea. 



III. The drainage of the Coal Measures region south of the Ouachita anticline 

 flowed westward, and entered this sea north of the Texas pre-Cambrian area. 



' Published in extenso in the American Journal of Science,^. November 1897, 

 iv. 357-371. 



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