Geological Notes | Nature

Geological Notes | Nature

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ABSTRACT OBSERVATIONS have been made by Mr. R. D. Oldham on the growth of sandhills, which threaten to cut off communication between the town of Karachi and the suburb of Clifton, two or three miles distant (_Mem_. Geol. Surv. India, xxxiv., part iii.). He traces out the growth of dunes from small oval patches of sand which begin to accumulate on irregular tracts of the stony surface, pointing out that even a slight accumulation may cause an upward bend of the air currents whereby a space of comparative calm is produced, and sand more readily comes to rest. In course of time the oval patches of sand are heaped up with a sharper slope to leeward, down which the sand grains fall. Here a hollow is produced by an eddy of the wind, and this eddy serves to maintain and increase a crescentic form with a crater-like opening. The principal winds at Clifton blow from W.S.W., and form the main features in the sandhills; but winds from the E.N.E. blow during the winter months, causing a reverse slope and a bank of sand to be formed near the summit of the long gentle slope which faces the W.S.W. winds. There is agood deal of scour of the original steep leeward slope, but no complete reversal of the shape of the sandhill. Access through your institution Buy or subscribe This is a preview of subscription content, access via your institution ACCESS OPTIONS Access through your institution Subscribe to this journal Receive 51 print issues and online access $199.00 per year only $3.90 per issue Learn more Buy this article * Purchase on SpringerLink * Instant access to full article PDF Buy now Prices may be subject to local taxes which are calculated during checkout ADDITIONAL ACCESS OPTIONS: * Log in * Learn about institutional subscriptions * Read our FAQs * Contact customer support RIGHTS AND PERMISSIONS Reprints and permissions ABOUT THIS ARTICLE CITE THIS ARTICLE _Geological Notes_ . _Nature_ 69, 138–139 (1903). https://doi.org/10.1038/069138a0 Download citation * Issue Date: 10 December 1903 * DOI: https://doi.org/10.1038/069138a0 SHARE THIS ARTICLE Anyone you share the following link with will be able to read this content: Get shareable link Sorry, a shareable link is not currently available for this article. Copy to clipboard Provided by the Springer Nature SharedIt content-sharing initiative

ABSTRACT OBSERVATIONS have been made by Mr. R. D. Oldham on the growth of sandhills, which threaten to cut off communication between the town of Karachi and the suburb of Clifton, two or


three miles distant (_Mem_. Geol. Surv. India, xxxiv., part iii.). He traces out the growth of dunes from small oval patches of sand which begin to accumulate on irregular tracts of the


stony surface, pointing out that even a slight accumulation may cause an upward bend of the air currents whereby a space of comparative calm is produced, and sand more readily comes to rest.


In course of time the oval patches of sand are heaped up with a sharper slope to leeward, down which the sand grains fall. Here a hollow is produced by an eddy of the wind, and this eddy


serves to maintain and increase a crescentic form with a crater-like opening. The principal winds at Clifton blow from W.S.W., and form the main features in the sandhills; but winds from the


E.N.E. blow during the winter months, causing a reverse slope and a bank of sand to be formed near the summit of the long gentle slope which faces the W.S.W. winds. There is agood deal of


scour of the original steep leeward slope, but no complete reversal of the shape of the sandhill. Access through your institution Buy or subscribe This is a preview of subscription content,


access via your institution ACCESS OPTIONS Access through your institution Subscribe to this journal Receive 51 print issues and online access $199.00 per year only $3.90 per issue Learn


more Buy this article * Purchase on SpringerLink * Instant access to full article PDF Buy now Prices may be subject to local taxes which are calculated during checkout ADDITIONAL ACCESS


OPTIONS: * Log in * Learn about institutional subscriptions * Read our FAQs * Contact customer support RIGHTS AND PERMISSIONS Reprints and permissions ABOUT THIS ARTICLE CITE THIS ARTICLE


_Geological Notes_ . _Nature_ 69, 138–139 (1903). https://doi.org/10.1038/069138a0 Download citation * Issue Date: 10 December 1903 * DOI: https://doi.org/10.1038/069138a0 SHARE THIS ARTICLE


Anyone you share the following link with will be able to read this content: Get shareable link Sorry, a shareable link is not currently available for this article. Copy to clipboard


Provided by the Springer Nature SharedIt content-sharing initiative