west and crosses the state line into Arkansas finally pouring its waters into the St. Francois.
West of Crooked creek a number of other smaller streams flow into the alluvial district. The first of these of importance is Castor river which enters the alluvial district near Zalma in Bollinger county. Castor flows south and southeast through parts of Stoddard and New Madrid counties and finally empties into Little river.
Two other streams of importance having their source in the Ozarks make their way through the alluvial district. The easternmost of these, the St. Francois river, leaves the hills in the edge of Wayne county and flows directly through Stoddard and forms the state line between Dunklin county and Arkansas. West of St. Francois river, Black river enters the alluvial district at Poplar Bluff. It, together with a number of smaller tributary streams, most of them rising in the hills, cross the state line into Arkansas from Bollinger county.
Besides these more important streams there are several other smaller ones such as Varner river, Buffalo creek, Taylor slough, and Chilleteeaux in Dunklin county, Pemiscot bayou in Pemiscot county and Portage bay and Open bay in New Madrid and Pemiscot counties.
With the exception of part of the sand ridges in Scott, New Madrid, and Dunklin counties this entire alluvial section was formerly heavily timbered, the entire country being covered with a heavy growth of oak, gum, Cottonwood, hickory, ash and other varieties of trees in the higher portions, and with cypress in those parts of the bottoms where water stood. There are still vast quantities of timber in this section, but it is fast being denuded of its timber.
This alluvial region presents an interesting geological problem. Those who have studied the region are not in agreement as to how the vast Mississippi embaymeut was formed. It has been suggested by some students that this great plain stretching from the mouth of the Mississippi to Cape Girardeau and varying in width from five to forty miles, is a coastal plain formed by the action of the waves against the land surface. No doubt a plain so formed would bear some resemblance to the alluvial plain of the Mississippi valley, but it is difficult to believe that such a plain as this could have been formed by wave action; the resulting debris from the destruction of the land surface must have retarded the action of the waves long before they sculptured a plain extending so far into the land.
Without attempting to go into minute details the probabilities are that the alluvial section as it now exists is a river valley. Early in geologic times the head of the Gulf of Mexico was near the site of Cape Girardeau and there was thus thrust into the heart of the North American continent a great triangular gulf. This gulf has been filled with alluvial soil from Cape Girardeau to the present southern limit of the delta. It is not possible to determine how deep the alluvial deposits are since there have been made no borings deep enough to find the bed of rock. Certain borings made for artesian wells and at New Madrid for the purpose of finding support for a bridge, indicate that the alluvial soil is more than two hundred feet in depth though there is very good reason to believe that it is very much deeper than this. A boring made at Cairo, Illinois, extended to a depth of 1,200 feet without striking bed rock.
It is plainly evident that the amount of alluvial material deposited in this gulf is en-
