منابع مشابه
Kope and Fairview Ripple Marks: Brown and Adams Counties, Ohio
The directional data of cross-laminae and ripple marks in the Kope and Fairview Formations in Brown and Adams Counties, Ohio, show no statistically significant difference in mean orientation. The prevailing paleocurrent direction was towards the northnorthwest. A significant difference, however, exists between the wave lengths of the ripples in the Kope and Fairview. Ripple marks are larger in ...
متن کاملObservations of Aeolian Ripple migration on an Egyptian Seif Dune using an Inexpensive Digital Timelapse Camera
I report experiments on the observation of sand ripples on the Quattani dunes in Egypt using an inexpensive ($150) digital timelapse camera. Simple ripples in the fine sand had a wavelength of 10cm and propagated downwind (windspeed ~10m/s) at a speed of ~3cm/minute, and Y-junction defects moved one wavelength forward in the propagating ripple pattern over ~6 minutes. This defect propagation sp...
متن کاملFlume experiments on the migration rate of wave - formed ripple marks
The migration rate of wave-formed ripple marks was investigated using a twodimensional wave flume. Well sorted fine-grained sand (0.2 mm in diameter) was placed on a 1/20-fixed slope and an adjacent part of the horizontal flume bottom. The onshore migration rates of ripples and near-bottom orbital velocities were measured at three sites along the slope with different water depths and at one sit...
متن کاملBursts in discontinuous Aeolian saltation
Close to the onset of Aeolian particle transport through saltation we find in wind tunnel experiments a regime of discontinuous flux characterized by bursts of activity. Scaling laws are observed in the time delay between each burst and in the measurements of the wind fluctuations at the fluid threshold Shields number θc. The time delay between each burst decreases on average with the increase ...
متن کاملDynamics of aeolian sand ripples
We analyze theoretically the dynamics of aeolian sand ripples. In order to put the study in the context we first review existing models. This paper is a continuation of two previous papers[3, 4], the first one is based on symmetries and the second on a hydrodynamical model. We show how the hydrodynamical model may be modified to recover the missing terms that are dictated by symmetries. The sym...
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ژورنال
عنوان ژورنال: Science
سال: 1884
ISSN: 0036-8075,1095-9203
DOI: 10.1126/science.ns-3.54.172-b