Page:The American Cyclopædia (1879) Volume X.djvu/676

670 LOUISIANA ular, there are not many good harbors. The Chandeleur islands, which lie opposite St. Ber- nard parish, S. of Mississippi sound, and E. of Isle au Breton sound, form a good roadstead. Besides numerous ponds and lagoons among the salt marshes which line the S. shores, there are some considerable lakes, most of which are expansions of the rivers. Of these, the princi- pal are Caddo, Soda, Cross, Bodeau, Bistineau, Wallace's, Canisnia, Bayou Pierre, Spanish, and Black, in the northwest; Jatt and Cata- houla, S. E. of these ; Oalcasieu, Mermenteau, Chetimaches (or Grand), and Verret, in the south ; and Des Allemands, Washa, Maurepas, and Pontchartrain, in the southeast. The last two are expansions of the Ainite river. The state is abundantly supplied with large rivers. The Mississippi, navigable far beyond its lim- its, forms the N. half of the E. boundary, and then entering the state crosses it in a S. E. di- rection to the gulf of Mexico, its mouth form- ing a delta. About 800 m. of its course be- long wholly or in part to Louisiana. It begins to send off branches to the gulf on the west near the point where it enters the state ; the Atchafalaya river is the first, and the entire region between it and the main stream may be said to belong to the delta. Among other deltoid streams are Grand river and Bayou de Large, connected with the Atchafalaya, Bayou Terrebonne, and Bayou Lafourche. These are mostly navigable throughout at high water. Bayou Teche, navigable at high water, emp- ties into the Atchafalaya from the west, and by means of Bayou Boeuf is connected with Red river above Alexandria. E. of the Mis- sissippi the principal streams are the Amite (navigable by small steamers for 60 m.) and the Tickfaw, which flow from Mississippi into Lake Maurepas ; the Tangipahoa and the Ohif unctee, which discharge into Lake Pontchartrain ; and the Bogue Chitto, which falls into the Pearl. The navigation of the Pearl is obstructed by sand bars and drift wood, but small boats as- cend into Mississippi. In the S. W. part of the state are the Mermenteau and Calcasieu rivers, which rise by numerous branches in the prairie region S. W. of Red river, and after expand- ing into the lakes of the same names discharge into the gulf of Mexico. The Sabine receives numerous small tributaries from the east, and is navigable at high water in portions of its course by small boats. The Red river enters from Arkansas in the northwest, and joins the Mississippi near the outflowing of the Atcha- falaya. The navigation of the Red river is somewhat obstructed at the mouth, but steam- ers ascend at all seasons to the falls at Alex- andria, and during eight months of the year to Shreveport, above which the " great raft " has hitherto been a bar. This obstruction was removed by the United States govern- ment in 1873, but the effect of the removal upon navigation remains to be determined. The chief tributaries, which enter from the north, are the bayou Dauchite, which expands into Lake Bistineau ; Black lake and Saline bayous, which unite before entering the Red river; Little river, which enters Oatahoula lake ; and Black river, formed by the confluence of the Washita and Tensas. Most of these are navi- gable by steamers, and the Washita, which rises in Arkansas, is navigable beyond the limits of the state. Louisiana presents many features of geological interest. The only formations are the cretaceous, tertiary, and post-tertiary. The first underlies the whole state, but crops out only in the limestone hills of St. Landry and Winn parishes. It comes very near the surface at the salt wells in Bienville, Natchitoches, and Winn, and is the formation to which the sulphur of Calcasieu parish and the rock salt of Petit Anse belong. The tertiary presents the divisions which in Mississippi have been called the Jackson, Vicksburg, and Grand Gulf groups. The Jackson group occupies the N". W. portion of the state, except immediately along the Red river and one or two of it8 tributaries, as far E. as the Washita, and oc- curs in two isolated localities on the Arkansas border just E. of that stream. It consists of marine strata with the characteristic fossils, of lignitic beds, and of non-fossiliferous beds of laminated sands and clays. Gypsum, lime- stone, and iron ore occur. The Vicksburg group occupies a belt not more than 12 m. wide, S. of the Jackson, and running S. W. from the Washita river to the Sabine. It consists of smooth clays and clayey sands, full of marine fossils. Lignite and estuary beds occur in some localities, yellow and white limestone nodules are common, and iron ochre abounds. S. and S. W. of the Vicksburg is the Grand Gulf group, stretching in a widening belt from the Washita to the Texas border ; it also occupies the K portion of the region E. of the Mississippi. This group consists of mas- sive clays, clay rocks, and sandstones generally of poor quality, with no organic remains ex- cept those of plants. The post-tertiary also, as in Mississippi, comprises the drift, the bluff, and the alluvial formations. The deposits of the drift period cover the formations already described, except parts of the Vicksburg group, and consist of various alternations of red and yellow sands and clays, with pebbles, general- ly flinty, but often of iron ore. The bluff for- mation, besides some isolated localities, occu- pies a considerable area in Franklin, Richland, and Carroll parishes in the northeast, as well as the region W. of Opelousas, lying S. of the Grand Gulf group and N. of the marshes. It also forms a belt just N. of Lakes Pontchar- train and Maurepas, stretching from near Pearl river to the Mississippi, thence up that river to the state line, enclosing the Grand Gulf group on the north and east. It consists chiefly of blue clays and fine sands, often con- taining shells of recent species, or of very fine grained, hard-pan clays of light buff or gray- ish color, varied in a few localities by a fine silt, sometimes calcareous, with snail shells.