getting data from next line and printing 1

[CooperS]

I have a datafile

1000 sandstone
1010 clay
1015 salt
1020 salt

I want to process this file to create the following output

1001 1010 sandstone
1010 1015 clay
1015 1020 salt

I would appreciate any suggestions as to how to achieve this with sed/awk

Thank you

 

[CooperS]

REVISION
This is the required output (1000 not 1001)

1000 1010 sandstone
1010 1015 clay
1015 1020 salt

 

[PHV]

Something like this ?
awk '{if(NR>1)print s,$1,t;s=$1;t=$2}' /path/to/input

Hope This Helps, PH.
Want to get great answers to your Tek-Tips questions? Have a look at FAQ219-2884 or FAQ222-2244