GEOLOGY OF LUCAS COUNTY [Iowa]

Lucas county is in the south-central part of Iowa just east of a north and south line through the central part of the state and in the second tier of counties from the IowaMissouri line. Its position in this tier of counties is sixth east of Missouri river and also sixth west of Mississippi river. Warren and Marion counties are on the north, Monroe county is on the . east, Wayne county on the south and Clarke county on the west. It corners with Appanoose county on the southeast and with Decatur county on the southwest. This is one of the smaller counties of the state and is rectangular in shape. It contains twelve congressional townships, with approximately 432 square miles or 276,480 acres.1 The twelve congressional townships are everywhere conterminous with the civil townships, each containing thirty-six sections, and comprise townships 71, 72 and 73 north and ranges 20, 21, 22 and 23 west of the Fifth Principal Meridian. The latitude and longitude of the Court House in Chariton, the county seat, are 41° 00\u27 55 N. and 93° 18\u27 22 W. This county is underlain by formations of the Des Moines series of the Pennsylvanian system\u27 arid\u27 has become an important coal producing county in the last few years. It is served by main lines of the Chicago, Rock Island and Pacific and the Chicago, Burlington and Quincy railroads

Some Large Glacial Boulders in Des Moines County, Iowa

The object of this paper is to record the occurrence of four large boulders previously unnoted. Their exact location is in a small ravine, near the middle of the northeast quarter of the southwest quarter of the northeast quarter of section 16, T. 72 N., R. 2 W., Huron township, Des Moines County, Iowa. This location is four and three-fourths miles northeast of Mediapolis and five miles northwest of Kingston. Des Moines County is in southeastern Iowa at the eastern end of the second tier of counties north of the Missouri boundary. Its surface is the dissected Illinoian glacial drift plain. Three glacial drifts are represented in the county, but it is believed that only the Kansan and the Illinoian occur in the vicinity of the glacial boulders under consideration

An Observed Origin of Some Mud Pebbles

Mud and clay pebbles and cobbles have been observed at many places by different people. They seem to be most common in recent stream deposits and are sometimes seen in eroded alluvial plain sediments. A few geologists have contended that the presence of these mud or clay pebbles in deposits indicates that the deposit as a whole was formed in connection with glaciation and at temperatures near or below freezing. The reason for this conclusion is the belief that balls of mud could not withstand the abrasive and disruptive action of stream transportation unless they were frozen and hard, simulating in that condition a fragment of indurated rock. This may be the history of some mud pebbles in some deposits but it is not a safe criterion on which to date a deposit of sediment

CLASSIFICATION OF THE TERTIARY SYSTEM IN NEBRASKA

This paper represents the results of almost continuous research by the Nebraska State Geological Survey on Tertiary stratigraphy in Nebraska during a perIod of more than 10 years, with special attention to the present acceptable stratigraphic nomenclature. Cogent reasons are presented for the retention of such well-known names as White River, Arikaree, and Ogallala, all now redefined and elevated to group ranking. “Loup Fork” and “Loup River,” Nebraska beds , and “Republican River are considered obsolete. The application of fossil seed zones to problems of correlation is noted. The table of Tertiary Formations of Nebraska summarizes the Tertiary stratigraphy in Nebraska

Some Observations on Undertow

Undertow has been the subject of considerable discussion among geologists and has received some attention in the press. Some hold that it is a continuous return flow of water along the bottom from a shoreline and others contend that it is a pulsatory return of water alternating with its piling up due to the shoreward movement of waves of translation

The Mississippian-Pennsylvanian and Pennsylvanian-Pleistocene Unconformities in Lucas County, Iowa

The object of this paper is to make accessible quantitative data on the magnitude of the Mississippian- Pennsylvanian and Pennsylvanian-Pleistocene unconformities in south-central Iowa. This data is here presented by permission of the State Geologist, Dr. G. F. Kay

THE GEOLOGY AND MAMMALIAN FAUNA OF THE PLEISTOCENE OF NEBRASKA PART I OUTLINE OF PLEISTOCENE GEOLOGY OF NEBRASKA PART II THE PLEISTOCENE MAMMALS OF NEBRASKA

The object of the present paper is to provide a suitable brief statement of the present state of knowledge of the Pleistocene geology of Nebraska, for an adequate understanding of the Pleistocene Mammal list, by Mr. C. Bertrand Schultz, which forms Part II of this report. The outline is necessarily brief and does not contain many detailed sections, nor lengthy discussions of controversial points. It is lacking in adequate detailed descriptions of new formations and may not be entirely convincing to many readers. The only excuse which the writer can offer for the shortcomings of the following pages is the necessity for brevity, and so the presentation is little more than a statement of conclusions

Discussion of a Sample of Cobble Gravel from the Mississippi River

The belief prevails in the minds of some that the Mississippi river is incompetent to transport pebbles of large size. The basis for this belief is the fact that the river seems to be carrying only relatively very fine material into the Gulf of Mexico. Therefore it seems that it is incompetent to transport material of cobble or gravel or even coarse sand grades in its lower course. Relatively coarse cobbles are transported along the river\u27s bed at least as far south as Cairo, Illinois