Chapel: Array of arrays vs 2-dim array on memory

In Chapel, it seems possible to declare an array by using the notation [][]. This looks very similar to "array of arrays" in other languages, so I am wondering whether it is a so-called "jagged array" with each sub-array allocated independently in memory? For example, in the following code, are a[0][..] and a[1][..] not necessarily contiguous in memory? (My interest here is whether the use of such [][] may be less efficient than [,] because of non-contiguous memory.)

proc test( D1, D2 )
{
    var a: [D1][D2] int;   // "jagged" array?
    var b: [D1, D2] int;   // I assume this is a rectanguar (contiguous) array

    for i in D1 do
    for j in D2 do
        a[i][j] = i * 100 + j;

    for (i, j) in b.domain do
        b[i, j] = i * 100 + j;

    var lo = D1.low, hi = D1.high;

    writeln( "a = ", a );
    writeln( "a[ lo ] = ", a[ lo ] );
    writeln( "a[ hi ] = ", a[ hi ] );
    writeln();
    writeln( "b = ", b );
    writeln( "b[ lo, .. ] = ", b[ lo, .. ] );
    writeln( "b[ hi, .. ] = ", b[ hi, .. ] );
}

test( 0..1, 1..3 );

$ chpl test.chpl
$ ./a.out

a = 1 2 3 101 102 103
a[ lo ] = 1 2 3
a[ hi ] = 101 102 103

b = 1 2 3
101 102 103
b[ lo, .. ] = 1 2 3
b[ hi, .. ] = 101 102 103

A related question is: Is there any way or command to know the memory location (address) of a given variable or array element (to get information on memory allocation)?