20 PROCEEDINGS OF THE INDIANAPOLIS MEETING. 



The paper was discussed by W J McGee, E. W. Claypole, C. L. Herrick, 

 A. Winchell and H. S. Williams. 



A recess was then taken until 7.45 p. m. 



After reassembling in the evening the Society listened first to — 



THE GEOTECTONIC AND PHYSIOGRAPHIC GEOLOGY OF WESTERN ARKANSAS. 



BY ARTHUR WINSLOW. 



The memoir was discussed by I. C. White, J. C. Branner and W J Mc- 

 Gee. It is published elsewhere in this volume. 



In the absence of the author, the following paper was then read by Mr. 

 W J McGee : 



THE NITA CREVASSE. 

 BY LAWRENCE C. JOHNSON. 



The Nita plantation is about two miles above Convent station, on the L., N. O. 

 and T. railwa}", and the landing of the same name on the Mississippi river. It is 

 opposite the head of Blind bayou, a sluggish affluent of Amite river which joins it be- 

 fore reaching Lake Maurepas, after, in a sense, draining the back swamps of that 

 region (fig. 1). This sluggishness of current in Blind bayou and neighboring water- 

 ways should be borne in mind as explaining the length of time before the back 

 swamps were filled up and the lakes reached by the flood, despite the extraordinary 

 force of the current (15 miles an hour) at the Nita crevasse. The first break began 

 March 13, 1890 ; yet it was not until March 22, nine days later, that the water came 

 through the south pass of Manchac (the bayou or strait connecting Lake Maurepas 

 with Lake Pontchartrain), and two weeks more passed before Lake Maurepas over- 

 flowed the lowlands to the northeastward sufficiently to threaten the track of the 

 Illinois Central railway ; and it was not unti.l April 13, or a month after the break, 

 that this railway was covered so deeply as to stop the running of trains. The water 

 now quickly spread over the whole of the flat country from the 28-mile post north of 

 New Orleans to the 46-mile post, or to within one and a half miles of Ponchatoula 

 station, and trains ceased to pass over this line till June 23. The greatest height 

 attained here by the river water was only eight and a half feet above mean tide, or 

 the ordinary low-water stage of Manchac. 



Ordinary maps do not show the well-known fact that the banks of the river, of the 

 bayous, and of lakes Maurepas, Pontchartrain and Borgne are higher than the back 

 swamps immediately adjoining, and that the Mississippi river at the Nita crevasse 

 is (by estimate) twenty-one feet above the swamps about Lake Maurepas. It is 

 reasonable to suppose that in locating the Illinois Central railway the highest ground 

 was selected ; yet until surveys were actually made it was not suspected that the low- 

 est ground is not the banks of Manchac, nor yet the quaking bogs to the south of it, 

 but the apparently firm land of the " pine meadows " or prairies to the north, between 

 the bayou and Ponchatoula.* 



* It is a pleasure to acknowledge the courtesy of Captain Mann, superintendent of the Illinois 

 Central railway, in furnishing data relating to altitudes as well as many facts connected with the 

 late overflow. 



