Lunar samples record an impact 4.2 billion years ago that may have formed the Serenitatis Basin

Impact cratering on the Moon and the derived size-frequency distribution functions of lunar impact craters are used to determine the ages of unsampled planetary surfaces across the Solar System. Radiometric dating of lunar samples provides an absolute age baseline, however, crater-chronology functions for the Moon remain poorly constrained for ages beyond 3.9 billion years. Here we present U–Pb geochronology of phosphate minerals within shocked lunar norites of a boulder from the Apollo 17 Station 8. These minerals record an older impact event around 4.2 billion years ago, and a younger disturbance at around 0.5 billion years ago. Based on nanoscale observations using atom probe tomography, lunar cratering records, and impact simulations, we ascribe the older event to the formation of the large Serenitatis Basin and the younger possibly to that of the Dawes crater. This suggests the Serenitatis Basin formed unrelated to or in the early stages of a protracted Late Heavy Bombardment

Some notes on Echinochloa

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Notes from the herbarium of the University of Wisconsin. X

Volume: 35Start Page: 387End Page: 39

Notes from the herbarium of the University of Wisconsin[long dash]II Bidens connata and its varieties in Wisconsin

Volume: 30Start Page: 31End Page: 3

A manual of plants

ix, 405 p. : il.; 23 cm

Notes from the herbarium of the University of Wisconsin[long dash]VIII

Volume: 34Start Page: 95End Page: 9

Rumex and polygonum in colombia

Rumex and Polygonum, of the family polygonaceae, occur in some abundance both in Colombia and in the United states, and this paper is an attempt to correlate a study of the Colombian plants with what has been observed in the United states. Through the courtesy of Dr. William R. Maxon, Curator, the facilities of the United states National Herbarium have been made available, and this work has been financed by the Wisconsin Alumni Research Foundation of Madison, Wisconsin. The writer's collections and field observations were made in Colombia from March to December, 1944, during such times as would not interfere with his work for the Colombian Cinchona Mission. Mr. E. P. Killip, Dr. F. R. Fosberg and Mr. Joseph Ewan have given me the benefit of their experience in South American botany to make a number of helpful suggestions.Rumex and Polygonum, of the family polygonaceae, occur in some abundance both in Colombia and in the United states, and this paper is an attempt to correlate a study of the Colombian plants with what has been observed in the United states. Through the courtesy of Dr. William R. Maxon, Curator, the facilities of the United states National Herbarium have been made available, and this work has been financed by the Wisconsin Alumni Research Foundation of Madison, Wisconsin. The writer's collections and field observations were made in Colombia from March to December, 1944, during such times as would not interfere with his work for the Colombian Cinchona Mission. Mr. E. P. Killip, Dr. F. R. Fosberg and Mr. Joseph Ewan have given me the benefit of their experience in South American botany to make a number of helpful suggestions

Notes on the flora of Boothbay, Maine[long dash]II

Volume: 29Start Page: 14End Page: 1

Notes from the herbarium of the University of Wisconsin I

Volume: 29Start Page: 227End Page: 23

Notes from the herbarium of the University of Wisconsin[long dash]IV

Volume: 31Start Page: 49End Page: 5