Refer to the diagrams showing drainage patterns. Identify drainage patterns A and B. Differentiate between the underlying rock structure of drainage patterns A and B respectively.

1.a Stream order for each drainage basin From the figure, assign Strahler stream orders starting from the outermost tributaries. First-order streams are those without tributaries (terminal segments). For basin A: 4 first-order streams, 2 second-order, 1 third-order main stream. Thus, stream order of basin A is 3. For basin B: 8 first-order streams, 4 second-order, 2 third-order, 1 fourth-order main stream. Thus, stream order of basin B is 4. A: 3, B: 4 Step 1: 1.b Number of streams of each order Count streams per order for each basin. Basin A: Order 1: 4 streams Order 2: 2 streams Order 3: 1 stream Basin B: Order 1: 8 streams Order 2: 4 streams Order 3: 2 streams Order 4: 1 stream &A: Order 1 = 4, Order 2 = 2, Order 3 = 1 \\ &B: Order 1 = 8, Order 2 = 4, Order 3 = 2, Order 4 = 1 A: 4, 2, 1 \\ B: 8, 4, 2, 1 Step 2: 1.c Bifurcation ratio (drainage order) Bifurcation ratio R_b = (N_u)/(N_u+1), average over orders. For basin A: R_b = (4)/(2) = 2, (2)/(1) = 2. Average R_b = 2. For basin B: R_b = (8)/(4) = 2, (4)/(2) = 2, (2)/(1) = 2. Average R_b = 2. A: 2, B: 2 Step 3: 1.d Stream order relationship (Horton's law of stream numbers) Horton's law: Number of streams N_u decreases geometrically with order u, N_u ≈ R_b^k-u. Both basins show constant R_b = 2, so number halves each higher order. Both conform to Horton's law. A: Conforms (R_b=2 constant), B: Conforms (R_b=2 constant) Step 4: 1.e Stream lengths (Horton's law of stream lengths) Observe from figure: Higher order streams are visibly longer. Mean stream length L_u increases geometrically with order, L_u ≈ R_l^u where R_l >1 (length ratio). Lengths approximately double per order (visually). Both conform. A: Increases geometrically with order, B: Increases geometrically with order 1.b Drainage density Drainage density D_d = Total stream length LBasin area A. No scale provided, but visually compare spacing. Basin A: Streams moderately spaced, medium density. Basin B: More streams, closer spacing, higher density. Total (combined or average): Medium to high (qualitative, no numerical values given). Or if grid/count method intended: Estimate L by segment count, A by enclosure. But figure lacks scale; typically described as: A: Medium drainage density B: High drainage density A: medium, B: high